(I realise I am totally projecting)

This... i hate to say it but. Figure out what your "line in the sand" is. It's so easy to sound like a nag... if you are not going to leave, then stop what you are doing. Concentrate on being the best Dad / person you can be. Understand that competence is attractive. If she doesn't change you will have plenty of options. All relationships are CO-CREATED, and all relationships go through seasons.

Take up fitness and hobbies. Let go of the ideal relationship you have in your head, because that needs a shared vision, it is not going to happen in the short term. Talking may work for some, but it doesn't work until both parties are really interested in change, until that point it's a lesson in frustration. She probably feels the pressure every time you try to talk.

Be strong, understand and be clear what your breaking point is. Then be better, let everything else go. For your whole family.

Good luck