The most confusing relationship. What should I do? Please help.?

Right here goes.I am 28 & got married when i was 24 after being with a woman for 7 years. We bought a house together & things were going well untill (without going into details, although don't trust your friends!) it didn't work out. Anyway I ended up with the house &a huge mortgage& not a lot of money after the divorce. So I decided to get a lodger. Taking a recommendation from a friend I took in a lovely girl from finland who came here to do nursing. We got on well &things were great, I had enough money to pay the mortgage &she was just happy to be here. Then after several months of not being able to find a girlfriend, we got drunk &slept together. Now she's infatuated with me &I have allowed things to get too far, we are living like a couple. I think she's really lovely but I find it hard to find her physically attractive &I just dont have the feelings I think I should have.Please don't call me shallow. I cant pay the mortgage if she moves out though. What should i do for the best?