J.B.
Well I can answer sort of from the other perspective. My husband and I each have a child from a prior relationship but we were not married to our child's other parent. My son's father is not part of our lives so it's a non-issue in my marriage. My husband's daughter's mother, though, is very much an ongoing part of our lives and I can't imagine not talking about the issues he (really, WE) have with her. Her decisions affect my stepdaughter/his daughter and she is as much a part of my family as my bio kids, so why wouldn't I want DH to keep me in the loop regarding what she's up to? I think that you and your husband should openly talk about your ex. He is a part of your children's lives and a part of BOTH of your lives now and always will be.