Broke up with live-in girlfriend, but she is still living here....What do I do? (M25 F26)

This girl still loves me even though I broke her heart. I don't know why....

Anyway she says she has no where she can stay until she can afford an apartment of her own. I feel bad about this, so I'm letting her stay here.

The thing is, we now have this mixture of bittersweet fleeting passion and resentment.

I'm confused.

EDIT: we just had sex....I'm worried that I'm breaking her heart by giving her hope.