Hello Morningstar.
I'd repeat everything Adifferentme suggested; try and extend your networks, little step by little step, be aware it's hard at first, and slow, daunting work, but so worth it; negotiate some time to yourself whilst your dh does a bit more. If he's off doing footie, then you should be getting (at least) equal recreational time.
As regards your relationship. Hmmm. Well, sadly, it is really hard to diagnose with the info. to hand and also with the age of your dc. There is no doubt that with dc this age life is hard and it takes a terrible emotinal toll on your relationship.
Going on your post, and only on that (I don't have any insight to your situation,) you sound very ground down. It might well be that being able to care a bit more would rise in direct relation to how much autonomy, freedom and self-hood you are able to get back in your current role, either as a SAHM or p/t working.
So I think it might be a really good idea to really try and negotiate some more time and space to yourself. If you are just being pushed into f/t caring and nothing else, no wonder you look at him and all you see is an image of something you don't have. Most people would resent that.
Does he share childcare and related tasks when he's around?