Us as women can quickly and quietly grow to resent some things that once didn't bother us.
As a woman I must say that 1: you shouldn't have moved in before you were ready for it. 2: at this point you are serving a purpose for her and the kid. If she doesn't at least attempt to rectify a "sexual" complaint, it's because she doesn't care. A lot if women don't like that particular act, but it's done to please our spouses no matter how much we don't like it.
I think you moved into this whole thing too soon. She seems more like a long lasting "rebound" chick than a wife.
I don't believe you should be contemplating anything except what's available to rent somewhere else and how soon you can move into the place.
Nothing that isn't completely 50/50 in all aspects will deteriorate any relationship. Money, sex, comfort whatever..... You don't seem to have approached this whole thing maturely from jump