1) very, very rarely.  It is hard enough for a non-personality disordered individual to effect lasting change, let alone a narcissist, who normally think they are perfect and don't need to change.  

2) can't answer this - it's very individual.

3) I was a relationship counsellor for 8 yrs and it did help some, yes.  But people usually come too late, when one of them has already mentally left the relationship.   You might want to give it a try, if only to satisfy yourself that you did everything you could.  

1.) If a person doesn't see their certain behaviors as a problem then no they will never understand the need to work on them.
2.) Leaving will hurt regardless of how its done.
3.) I think it can if both parties are invested and really want to work for their relationship. I know for me when I check out no amount of therapy is going to get me to reinvest in something I have already deemed over and done.

1. No

2. It is very hard to leave a true narc. And when they don't want you to leave they will try to destroy you. They will lie about you and tear you down.

3. Counselling might help. YOU.

Make a plan to leave without anyone's knowledge. You deserve to live a life that works for you.

Once he realized I was sick of his selfish, druggie life and I was on the way out with our 2 kids, my ex suddenly wanted to go for marriage counseling.  If he had suggested this a year earlier, it might have bern effective.  But he wouldn't have done it then, too much trouble and he was happy with how things were going.  We went once but even the counselor knew I was halfway out the door and could probably tell that my ex didn't really want to change anything other than my mind.  So, I agree with Kes, maybe go once and you can tell yourself you made the effort.  Perhaps when your DH sees how serious you are, he might make some changes but I wouldnt hold my breath.  Sorry, Simpleton.

When DH and i were up against the wall over the SK issues, I suggested marriage counseling but he refused to go so I went myself.  It was the best money I ever spent.  I remember saying tearfully while making the appointment, " There are 5 kids involved".  Two of my takeaways were assertiveness and more one-on-one time with DH but the assertiveness was the biggest thing.  Contrary to what we often see on ST, I needed to engage more, not less.  It was more about claiming my place.  Whatever it was, it changed my life.  Months later, as DH and I spoke about it, I remember telling him. "Its bigger thsn just you and me", ie, it was my personal growth.

So, yes, you are definitely, positively a wonderful candidate.  For it to be effective, 1) you need to be able to recognize mistakes and 2) be willing to change.  You are there on both counts.  Why not call today?

1.) The question isn't can they change, it's can they change enough to be the person you need them to be. I do think people can change because I have forced myself to change, and have seen others change, too. But, someone getting better doesn't mean it's good enough. You don't owe anyone lowered standards just because they couldn't meet your (reasonable) expectations.

2.) If you decide to leave, then leave. Have as best a plan as you can beforehand. Draw up divorce papers and have them ready to sign. Be equitable in what you want. Keep communication through an attorney. Inform close family and friends that is happened, but let them know how much you want or don't want to talk about it. Don't talk to your STBXH after you leave, but do provide him with closure before you do (this can be done in a letter; you don't have to verbally spell it out). Block him once your gone.

My biggest regret with divorcing my XH was not cutting the cord and filing ASAP after I left. I WANTED him to get "better". I WANTED to go back to him. I ended up with 6 months of texts, phone calls, and visits that ranged from him showering me with love and gifts to calling me every nasty name in the book. And this would happen at all hours of the day and night. It finally stopped when he got a GF.

Also, don't agree to not tell people that you're getting divorced. I agreed to not say anything to mutual acquaintances and his family, and they found out we divorced when his new GF posted that they were in a relationship on Facebook. I had people crawling out of the woodwork asking what was going on, and I felt that I needed to apologize and have closure with his family. It was a mistake keeping it a secret, though you're under no obligation to shout it from the rooftops, either. 

3.) Yes, go to personal counseling. Whether or not it works is dependent on the kind of person you are. I felt a lot of guilt around leaving, and I was damaged in a lot of ways that I didn't realize from that marriage. I have worked through a lot of it on my own, but it would have been better and faster had I actually talked to someone. Worst case scenario, you find out therapy isn't your thing and you waste a few hours of your life trying to better your life. There are far worse ways to waste a few hours.

I'm still here :)  I try and stop in daily to keep up and see how everyone is doing

1)  Even with my situation I fully believe people are capable of change IF and only if they WANT to change and actually STRIVE for it.  THey can't just say they'll do it.  They have to actively work towards it if they want to change. Sadly I don't think most people do, and if the threat of losing the person they supposedly love isn't enough for a reason, then nothing ever will be.  If someone wants to change they very simply will. 

2) It's always going to hurt, I won't sugar coat it.  You don't mourn what you have even, you're mourning the potential of what could have been.  Best advice is to take the time to get your ducks in a row.  Mine werne't super in a row, but prior to filing, I DID make sure anything I truly cared abour (stuff from my great grandparents) were out of the house.  Also be sure you have somewhere to go.  You can try counseling if you'd like as well just to be sure it's what you want.  BUt the second you make the decision you really know that's what you want and need.  It's like a switch flips a bit and everything you knew but wouldn't admit starts to hit you.  Best advice is just making sure it's what you want

3) I think counseling can work.  IN my situation it would have if he had actually taken the advice of the counselor.  Unfortunatley (or fortunately? I am happier.) my ex didn't want to change, didn't want to put in the effort, and instead took every crticism as the counselor and I being out to get him.  Same as with changing, counselor requires the participation of both parties.  He'll have to want to change and put in the effort to do so.  And you'll have to be in it as well.  If you're only half there then neither party is ever going to make enough changes.

He has to go to a professional person.  If he really wants to change,   Not Joe down the street in that Bar and grill 

If he wants to change first he has to understand he needs help then do something about it 

OP, I am both happy and sad to hear this. Happy because you decided for YOU that you need happiness, not just..."well, it's ok" for yourself. Sad because you are with someone like this to begin with. 

He is someone like this. You know, I have never waffled back and forth thinking someone may be a narcissist and it turned out they were not. I have gone back and forth about someone being a narcissist when they were a narcissist - it's part of what narcissists do to your thinking...they make you question your thoughts on everything,  including if they are a narcissist.

I am worried that you have told him you want a divorce and for him to leave and he refuses. Ultimately, he thinks it is his decision and when you push it, there will be no mistake on his narcissism. It will come out in full force. Mentally prepare for that - he will likely try to destroy you - ripping you to shreads, your character, how "you wronged him" (and probably his kid). I can't remember if you have a shared child... I think so, but damn I hope not. He will be very jealous YOU get to stay in the house (thankfully you haven't bought it from your dad yet!). You may want to consider cameras.  

My ex-husband is a narcissist (and abusive, abusive as marriage went on and got worse when divorce). It was HARD leaving him (had to kick him out of MY house). It took 5 years to get divorced. He did many cruel and harassing things. Truth be told, he still does. Actually today something happened - something that if I tried to report, it would be blown off, excuses made, attempts to make ME look crazy.

I fear since he will not be getting a reaction, he will ramp up his behavior until he gets one - because he is angry that I know his truths (I discovered A LOT of stuff while preparing for and during divorce - deep dark secrets). He "wants revenge". He sees that he was wronged and acknowledges nothing of what he did wrong to me. Because in his mind the story has been rewritten, and he actually tells the story so many times that he believes it. He is more than "just a narcissist" - he is a malignant narcissist. 

Try your best to get him 100% out of your life as fast as possible. I truely hope he doesn't hang on to vengeful feelings as my ex has, and will, until he has someone else to turn his hate to (when he divorces again... I was his FOURTH wife, unknowingly, he lied about how many times he was married previously).

Was when Chef realized his own mortality after the doctor said he is about to stroke out or having a heart attack before he is age 55.

Up to that point he childishly viewed himself as immortal and could do anything he wanted without repercussions.

In other words they have to take the initiative on making a change otherwise all the pleading and cajoling in the world will do nothing.