NOOOOOO... Especially in high conflict situations... Where there's still clearly lots of dissagreemont on BOTH sides. I honeslty think your bf is probably right in this situation... She likely won't respond positively, and will possibly accuse you of overstepping... Just let this one lay.

Stay out of it. I know it sounds like it might be a good thing to do, but if the ex and your BF don't get along, she surely doesn't want to be talking to you.

Don't do it becaause it could make things so much worse. She is more likely to consider that you are overstepping that extending an olive branch. Do not interfere with this situation.

welcome! Glad you’re here! I have never met my dh ex and never will. Since I came into my dh life a year ago I have slowly integrated alterations in how dh interacts with bm and eventually made it so that there is zero interaction between him and her due to us having a 3rd party drop off and pick up point at the same times every week. Bm’s are vile creatures that are not emotionally stable enough to be rational. They are typically not over the marriage and harbor deep anger. Please do not interact with her at all, ever and look for ways to alter your dh’s communication style to lessen the communication between him and bm. You want her toxicity out of your life. Be happy and do not get involved at all with bm, ever. Good luck to you! 

Don't do it. Trust your BF on this.

I tried the "be friendly for the sake of the kids" thing against my DH's advice. What he said would happen is what happened. As soon as I said "no" about something, that was the end.

Look, if the animosity is already there when she doesn't even know you, or care to know you, then that is something she is going to have to come to terms with herself. You can still be polite and cordial if/when you see her, but you don't need to be her friend. If she hates you without cause, then the issue isn't you.

BUT, even IF you were all to become BFFs, your BF has to be the one to learn how to communicate with her and drive that co-parenting ship. Not you. Never you. Not your place. Not your job. Not your responsibility. EVEN IF YOU WANT IT TO BE YOUR JOB, it NEEDS to be his because this is about THEIR children. And THEIR children will look to THEM for guidance before they look at you.

What's best for the kids is for their parents to parent them, whether that be co-parenting or parallel parenting. They need to know that Dad and Mom are equal, even if their approaches are different. If you get in the middle, you take away part of your BF's authority and weaken his standing as a parent. Then, if you ever decide to disengage or leave, your BF no longer has equal authority to BM, which can lead to alienation and disrespect.

So, don't get in the middle. Support your BF in his efforts to be a good dad if you so choose. However, let him and BM figure out what kind of parenting relationship they will have. If you don't agree with their approach and it bothers you badly enough, then you can choose to disengage or leave. However, the choice to get in the middle should not be considered.

Don't do it.
Communication should be between the bio-parents.
By reaching out you are asking to get your hand smacked.
Don't blame BM when she does just that.
 

I communicate with the BM here, but there are some key differences. First, I did not reach out to her first; our relationship (which is limited to dealing with each other about skids) has developed over a few years. Second, she and DH are not HC.  She is also sane, not personality disordered and mostly (not entirely) reasonable. Also, I'm communicating about day to day logistics, since I'm the one who is home. Anything major is discussed and decided by DH and BM. I give my input to DH, but I'm invisible to BM on the big stuff.

In your case, with BM and your BF being high conflict, I would stay out of it, at least until you've been in the picture a lot longer and you have your BF's blessing to get involved. 

You aren't this guys wife or his kids' stepmother. Do not call BM. Focus on you and your boyfriend, and make sure you keep your eyes wide open before you marry him. If/when you do, still let the kids' father deal with his own ex. Save yourself the drama.

I am two fold on this. 

As a Bio mom of 2 kids, I found it much easier to communicate with their SM than my ex. She and I are similar enough to "get" each other and we work well together. Sometimes I forget to even include him on e-mails and she and I text all the time.

As a SM, I have tried multiple times to coordinate and help with communication with BM. I once even had a face to face with her and told her- "Hey, I get it. I think my exH is an idiot sometimes. That's why we aren't married any more, right?" I told her that I found it easier personally to talk to their SM, she is a mom too and has an exH too, so she sees things from both sides, much like I do. I told her that I would be more than happy to be the bridge in communication.

she played all nice to my face and has never spoken or looked at me again (2 years later). She also only sent my SS one more time after that. She does nothing but trash me. 

I took away her back up plan when I married my husband. I believe that she always thought she could play the "let's be a family" card and DH would take her back. So she hates me. 

Honestly I can't tell you. There are too many factors to consider. In our case there was almost no commuincation between the kids mother and myself for over a year. Finally there came a time when she wanted us to get the kids early and I had to be the one to go get them. At that point we still didn't talk and both of us were messaging SO to figure out what was going on. After that we started to communicate for exchanges alone and it kind of grew out of that. Now I'll send her a picture from time to time of the kids and she messages me directly for most things concerning the kids day to day. She'll message SO directly for major decisions but I handle the day to day so it's just easier. She has said she appericates me but we aren't best friends. We exchanges messages like we are coworkers and the children are the job. You can respect someone without being best friends.