The whispering is rude as hell and your husband shouldn't allow it. Enough of the excuses! 

She is only 10...the teen years will be even worse.

If your husband doesn't do anything to correct this and he keeps making excuses for her... your marriage likely will not last. 

If SD is whispering to Dad and not speaking to you, I'd tell him that she appears to have "selective mutism" and he needs to enroll her in counseling to fix this.

Your story sounds so very similar to mine. All I want to say is, if you really love your husband and want your marriage to work, take it one day at a time. Never show her that she upsets you, that will only make her enjoy it more. I once read an article in a magazine which says: she will finish school and leave the house one day, then you still have your marriage. My SD was also around 10 years old at that stage. I hold on to that article and it motivated me to to keep going. What I did not know at that stage, was the worst was yet to come. At age 14-17 was the worst. SD posted on social media about me. It was the most terrible years of my life. I thought of taking my own life many times, because I had stress at word and stress at home. DH got angry with me every time I wanted to discuss SD. When SD was 17, we went for councelling. The psychologist said its clear that BM was the mastermind behind SD's negative attitute. SD left school and home 7 years ago. Although I know we'll never be very close, we hug each other when we see each other and we can even have a civil conversation. Don't give up on your marriage. Don't give up on your DH. Get a nice hobby or something you can put your energy into and shift your focus away from the negative environment or situation. In a few years time, it will be all behind you. xx

Well, it's up to you if you want to stay with him. But most stepkids don't leave at 18, especially those who are enmeshed with their enabling father.

I personally would be civil and pleasant to her, but nothing more. And I sure as hell would not go out to dinner (or even eat dinner at home) with her. Or be in any other situation where DH allows her to be rude to me.

I'm pretty sure I'd also lose all love and respect for DH. Some people seem able to separate their partner's lousy parenting and enmeshment with his kids from their feelings for him, but I don't think I could do that.  I'd be very resentful and unhappy if I was blamed for his inability to be an effective parent to his kid.

"EXCUSE ME!  Speak up.  No one can hear you.  Whispering is rude so either speak up where everyone can hear or keep your mouth shut."  Lather...... rinse....... repeat.

I was a shy child too. But I sure as hell knew I had to say please and thank you and hello and goodbye and answer questions address to me.

What will this child do when she's in a new situation -- new school, college, roommates, job, boss, etc.? WIll Daddy be there to speak for her?

Your DH is crippling his own child by not teaching her to handle normal social interactions. She doesn't have to be a chatterbox, but she does have to engage in normal activities. What in the world does she think will happen when she says outloud, instead of whispering to her father, "please pass the potatoes?"

Hi, I appreciate your post. I came into the picture when my SD was 11 years old. In the beginning, I tried very hard to befriend her and get her to like me. It was ok for awhile until her dad and I married and she was 13. Then all hell broke lose.

I noticed she only acted as if she liked me when I said yes and gave her things. When I said no, I was "stepwitch" and "not family."  She would call her father a traitor. I was ignored purposefully. She stole clothing from my closet. She would purposefully do things to get under my skin, like saying, well dad's had many girlfriends or "this is my house." She would have angry outbursts, slam doors, throw things and scream at my husband. 

It's safe to say, kids that act like this have issues. They are angry and obviously not getting their needs met. Their PARENTS should be working on this via counseling, spending 1/1 time, etc.) 

If you feel that you are really trying, but it's making you unwell perhaps create bounderies and consider pulling back. It doesn't need to be drastic or dramatic, just matter of fact and polite. Here is what worked for me:

1. When she starts the bad behavior, disengage and "pleasantly" leave the room to find other things to do. I keep a list of things I'd love to work on or get done like my scrapbooks or catching up on work. When DH asks what I am doing, I just tell him that I didn't like the behavior and rather than getting upset about it, I decided to take a break.

2. Do NOT show your emotions, irritations, disgust, etc. That will just fuel the fire and give more ammo. It's hard, but I noticed if you ignore the behavior, it tends to dissapate. I also don't feel like I stooped to the child's level. When she makes the "dad has had many girlfriend comments"  to me or others, I lnow augh and say, "yeah, I did too...several!"

3. Not your kid, not your problem. You are not responsible for her development. If she doesn't have any friends, cannot adapt to situations, grow into a considerate person, that is for your DH to worry about. Be a sounding board, but don't get involved. Trust me, it won't help, work or do good for your marriage.

4. If she doesn't want to be nice or respectful to me, then she doesn't get anything from me. I don't make special meals, drive, purchase things, give or lend her things anymore. I no longer take the lead in birthday party planning, Xmas shopping, etc. I let my husband do that now.

 I used to include her in my familiy outings and dinner with friends. That has stopped. If she takes something of mine, I retrieve it and tell dad. (He can do the punishing with my input.) I keep her at a distance, politely. When she is being nice and behaves, I will find something in common to do with her like watch a movie. I limit it to an activity that doesn't include her getting material things from me. I never lend advice unsolicited, and if Ishe asksl, I am very conservative with my feedback.

I don't do all of this  to be mean. I do it to keep myself from being a martyr. It has helped my nerves and I am happier in my marriage too.