Wow yet another post that I could have wrote myself. It's amazing how similar things can be with so many different people. I know how hard it can be, I've walked in your shoes several times. With the credit cards, you have to be very careful, I made my wife cut hers up one time after I got a personal loan from the bank to pay them off & have just one lower interest payment. That worked great until Christmas rolled around then she started shopping on line where the web sites still had her CC info still stored, so then she maxed them all out again. As far as living together, not sure how the laws are in UK but here, If they are not on the lease or deed or whatever, then they are a guest & have to leave when you tell them to. I know that isn't what you want to do & would feel understandably guinlty about it, but she may leave you with no options. As for the sexual part, from what I have read here, it doesn't sound ucommon either. I know I have went through EXACTLY what you are going through. I don't know how many times I have heard thing like "come on let's just get this **** over with so I can go to sleep", & things like that. Or afterwords have tohear about how musch she hates doing that & the only reason she does is so I won't cheat. But then she wonders why I don't try to initiate things with her as much. I t has not been uncommon for us to go 2 weeks or more without doing it. There is always an excuse, one after another. I always try to let the things she says roll off of me, but a small part of you can't help but take it to heart & it can wreck havok on your ego.
Sorry such a long reply, I hope it was a little helpful anyway.