“What's wrong with being "housemates" at this stage of family life? 2 young DCs, what the fuck did he expect?
It's a phase, plenty of marriages get through it. He must really be stupid, I mean intellectually challenged.”
This. It is the reality of having children, particularly young children. It puts a strain on even the strongest relationships. But mature adults can normally work through their differences on the basis that the family unit comes first.
There may well be an OW in the wings who can massage his ego because she’s not having to do the hard work of co-parenting with him. It’s very immature and selfish. It also sounds like too much of the caring has been dumped on you because you were an SAHM.
Your marriage could be retrievable if he were willing to do the work but it doesn’t sound like he is - if he were, he should have raised his concerns much sooner.
This is very shocking and hurtful and hopefully you have some RL support to help you with the pain.
When you can, be as practical as possible because when you look back on this time, you will be grateful you were. In particular, protect yourself against him draining joint bank accounts and leaving you without financial resources. As PP have said, knowledge is power.
Above all, don’t beat yourself up for his decision. Nobody is perfect. I know I can be a royal PITA at times and so can my DH. So can everyone. This is almost certainly about his inability to cope with the reality of parenting. Nothing more.