I would have difficulty with his initial lie and his timing telling you about it. I can understand if his family has a relationship with the mother of his child; that's his parents grandchild whether or not the child is legitimate. I can also understand his paying for the child's support, that's his responsibility and I don't see that as extortion.

I don't think you can fight the family on who they care about. If he had been married and divorced from her, it would be no different so the married/not married/legitimate/illegitimate doesn't really matter.

My husband has an ex-wife and 3 sons and we're working on our wills and that's a little bit difficult for me too, despite my not really having anyone else to leave our money to, I'm loathed to have his son "control" half our wealth if my husband dies first and I'm still a bit young. He's 7 years older than I am.

Your husband has this relationship. That no one came to the wedding is not great either. That's not really support of him either, as he chose to marry you. That's extremely bad manners.

I don't know that there is a whole lot you can do except ignore the situation as it stands, unless you decide you don't like it, don't think his lying bodes well for your marriage to him, etc. I would not like anyone dictating whether I could get pregnant or not or what I could/could not do (gain weight). That doesn't sit well with me. You did not say what keeps you in the relationship/marriage? I don't see a partner, I see a really bad, controlling parent or sibling.