I really feel for you. Not sure how old your other kids are, but thankfully your child with your husband is too young to know what her dad is up to.
I’m the middle child of 7. I have 3 full siblings, 3 half siblings. You guessed it, my Dad had been having an affair for 5 years and my mum (who he was married to) was none the wiser until she bumped into his mistress while shopping. Both of them pushing babies that looked like they could be twins.
Bit of back story - Mum recognised the mistress as the ex wife of my Dads cousin who she had met at a party of one of dads relatives years earlier. At said party, mistress told my mum that my mum and dad would have beautiful children together. My mum says she knew from that day she had her eye on my dad. She saw her at occasional family gatherings until her and dads cousin divorced a couple of years later.
So mum gets home, mentions to my Dad that she bumped into so and so, he’s like who? She says you know cousin so and so’s ex. He’s like oh yeah, how is she? my mum replies with why don’t you ask her when you’re next there to see your new baby.
He splutters something about her being crazy with baby hormones and leaves the house. When he got back, my mum had packed his things and left them at the door and took us to our nans.
She divorced him a couple of years later (I asked when I was older why it took so long to divorce and mum and dad both say dad wouldn’t agree to the divorce) then he married the mistress the same year.
I’m guessing he didn’t want to divorce my mum cos he thought she would always be there until my mum threw him out and seeing as his mistress was happy to be just that he thought he would get away with it. He never spent the night with her. When I was younger he was always at home for bedtime, breakfast and school run etc.
The oldest of their children resented me and my siblings for years as he thought my dad had an affair with my mum - don’t know how he thought that as the oldest of us all is my full sibling. He also didn’t know that dad was married to my mum. He always thought that dad didn’t do bedtime and stuff with him when he was little cos we/my mum kept him away.
Turns out he used to visit his mistress and other kids when my mum would go to my aunts for Sunday lunch once a month. Those poor children only seeing their dad once a month :,(
I think in this situation, even though you are the one married to him - that he is treating you like you’re the mistress. Spending weeks if not months at time away from you and his little baby. You are his fallback option for when his “ex” gets sick of his behaviour.
I hope you find the courage and strength to get out of this really bad relationship. For yourself and for your children. The things they can pick up on even at a young age can be damaging.
So you all know - dad stayed married to the mistress. They’re both miserable but miserable together lol. Turns out monthly hook ups and getting knocked up do not make a happy marriage. But the mistress stuck with him and his bad behaviour, but I guess their bad behaviour is one thing they actually had in common (cos there’s certainly nothing else) cos she knew he was married to begin with.
Mum married a nice man about 25 years ago and is happy.
You can do this. You deserve happiness. You just need to find the strength to block out all the crap that comes out of his lying mouth!!!