Wife has Fibromyalgia. Son has Autism. Daughter has ADD. I have nothing.

Title says it all. Everything else in the house is a priority than me. Wife hurts. Son melts down. Daughter can't pay attention and acts out. School is a nightmare for both, they usually have some type of parental-call issue every week. Wife has near-constant flares of Fibromyalgia. Has plenty of energy to deal with the kids' drama and tribulations, but none for me. I work. That's what I'm good for in my house. I work full time and then 30-40 hours a week driving Uber. My wife "can't work" because she's so tired and hurting from dealing with the kids. I do most if not all of the housework because she's too tired/hurting. I do most of the cooking because she's too tired/hurting or a child is acting out. I would be the biggest shitbrain asshole if I left because the kids would have zero support and would probably be taken by the state, which I'm sure I would have to pay for. There's no f'ing way I could afford to have full custody of them and work my schedule. Intimacy? In my dreams. Literally, I wake up with a hard-on after a sex dream and my wife yells at me for "disrespecting her". Because she's tired and hurting, me wanting sex is "selfish" and "hurtful" to her. But then, when I'm really just about to get up the ultimate nerve and leave, suddenly she's on top of me, begging for dick, telling me that she doesn't know why she doesn't want to fuck all the time, I'm so big, I feel so good to her, orgasm after orgasm, put another baby in me, etc. Then when she feels I've come down off my cliff, back to business as usual. Jesus, what my life has become.