This is also going to irritate your husband and cause problems between you and him. Why let her have that much control over your life. Let him have his conversation without you right under him. Leave the room. Then when he's done, come in and give him a hug and kiss and suggest doing something fun.
Sex is always good.
Build his self-esteem rather than tear it down and you'll find he may become more aggressive with her on his own. In the beginning it will be easier for everyone if you allow him to spend time with his kids without you being around. After a few years that probably won't be necessary but at first when the kids visit, make yourself scarce unless they invite you along. They will invite you. Don't make them think you don't want to be around, make it clear that you feel they need time alone with their dad, if anyone needs you, they know where to find you.