Step Families Support Group
Traditionally, a stepfamily is the family one acquires when a parent enters a new marriage, whether the parent was widowed or divorced. This community is focused on many of the relationships and issues that may arise within stepfamilies where you may find answers from some members and you may help other members with their questions.

Divorce Poison & Step Monster.
They will change your life. It talks about PAS (Parental Alienation Syndrome) which sounds like what your husband's ex is doing. Remember you both have rights and you can get those children into therapy and try and combat that now.