I love my old fat neighbor. i love fucking her, anyway.

For the past 4 months I've been fucking my neighbor. An old fat horny bitch who lives alone in the apartment downstairs from me. She tells me that she is 65 but I think she is in her seventies. She has got big sagging tits, tree trunks for legs, and a huge, flabby ass filled with pock marks. Gross huh? But for some reason this turns me on. She gives a fantastic blow job. She swallows. I'm 35. Can this strange sexual attraction be normal? I tell nobody I know about this. I have a girlfriend that is going to moving in with me soon. She is 29. I think she would freak if she knew about this. It's strange, but could this be normal?