20+ years together and it's time to call it a day

[Takeheed]

But I don't know how.
We barely talk. Disagree on everything. He sleeps in the spare room. We both pretend it's because he snores but it's because of the lack of sex. I can't bring myself to sleep with him anymore. I have to have a drink first. I flinch when he comes near so he doesn't anymore.
He's chronically ill and doesn't work whereas I work full time. We have nothing in common.
I feel like he's gone a bit mad from never leaving the house as he's obsessed with conspiracy theories or alternative medicine.

I pay all the bills and support him.
I can't bring myself to say it's over. Why? ?? What the hell is wrong with me?
How do you even start to untangle from 20+ years and some sort of weird dependency ??
I don't know what to do i feel like I'm going insane.

Sounds difficult to say the least! I assume you love/loved him in some way or else you wouldn't be there. Why not look into some counseling for him and yourself? You might learn something that would help you move forward. He may need some emotional help, given his long illness, and you could use some support with such a complicated relationship.

You could try counselling if you want to try to fix things, or start making plans to leave if things have gone too far. You do sound totally fed up. Does he have any good qualities? Staying with someone because you feel sorry for them or because of the time invested so far isn't a good long term solution.

I'm sure he also realises this is like a flatmate arrangement now, except for the fact that a flatmate pays their way. That one point just wouldn't work for me and you have a million and one reasons to bring this to an end and get a life for yourself.

I can't imagine how miserable it must be in such a relationship.

Before his health deteriorates and you end up becoming a carer, you should call time on it. I presume he has some living relatives and if he doesn't, then he'll have to wake up to the reality of life.

What a dreadful situation for you both. You're going to have to be the one who ends it though, despite no sex, which would be a catalyst for most, he's living rent free & wont change

Have a read-up on co-dependency - do you recognise any signs in yourself? (Or not?). I'm not sure how realistic it is to stay with someone because you feel sorry for them.