The thing is this is wrong. And you have to act with decorum and grace and downright sneakiness.

The next time the kids are over make plans to go out (and away) with your child. Visit family or friends. Spend the day at the pool, stay in a hotel for the night. YP (Your Partner) will get pretty snotty and probably angry. But you simply tell him with a calm voice and no drama "Honey, you get 100% time with your children and I get 100% time with my child. See I have to share him/her with you and it isn't fair. So I spend time with my child and you spend time with your children. Oh and by the way, I expect not to clean up after them when I get back seeing you are on board with being the 100% father and not a percentage shared with your partner."

This is absolute nonsense and must stop. I get the he doesn't see his kids everyday, but as other posters have pointed out, he is doing them no favors by lavishing attention on them while ignoring your bio kid. If you want you all to be a family, he needs to start acting as if your are a family.

And if he is going to ignore your bio I have no idea why he'd object to you taking him out to do something fun. That's because he feels like you should be present also worship at the altar of your step kids?

I suggest counseling and right quick. It sounds like you have a guilty daddy on your hands.

While I feel sad for the baby, I can't help thinking this guy has warned you all along who he is and you wouldn't listen. Just from reading your previous blogs from 18 months ago before marriage and before you decided it was a good idea to have a child with this man, this man treated you poorly. He was also right upfront with you that his children were #1 with him and were to be his priority. Even back then you and DH had large differences of styles/opinions on parenting and disciplining.

I guess I don't understand why you thought this would all change just because you went ahead and married him and decided to get pregnant. I will ask, how are things now between you and husband and also as a family of three (now baby is present) during the other 26dys a month when the stepchildren are not visiting? Does he give this baby attention? Does he put any effort into making a home and family life for you and his third child?

IDK how old your baby is as 18months ago he/she didn't exist at all. So what? 6 to 15 months? How old are the older previous children? How do the all the children get-along? Do the older child accept and treat their younger sibling well? Is it DH doesn't want you to go off and take the baby away from bonding with baby's siblings or does he really just not want you to go and do something else while he visits with the older two.

I really don't know what to say/advice or even suggest what or how to make things 'better' for you with so much information missing from how you went from 18months ago to now and the why. Sure I could offer my 'oh that's not right' or 'oh, how terrible of Dad and you need to be a family on skid weekends', but I don't think that's going to be helpful. I can say , no, you're not overreacting and no, you're not wrong...what I can't say is what the solution is with so many unanswered questions hanging out there.