Well, I guess they've both told you just where you rank :O

What happened to your prior home? Do you still own it? I'd not live in a house where I felt froze out nor in one I couldn't consider my home. Is he willingly to sell or give his daughter this house and he and you purchase a home together if you intend to actually marry him?

Honest to God. Get out now before you get hurt any further. You SO will never change and it will only get worse. Go find a man who has a set of balls.

LIsten to luvmypuppy and let him pay all the bills and her for that matter if she thinks of it as her house.

Save every penny you can. If he decides he wants a life with you then you'll have money to put down on a house for both of you.

Needless to say don't get married until this is worked out.

OK so let me get this right. This is his ex-stepdaughter. His ex wife's child by another man. Is she alone in the world? Was he the only man she ever knew as Dad?
I am thinking his ex wife died. He cannot let the house go and throw this motherless girlwoman out into the world when she doesn't have any parental figure except him.

Or he got the house in the divorce and the girl is part of his settlement.

Either way he is either not in a place to move on with his life and let history remain in the past. If his ex died of course there will be memories. But if you are not prepared to let go some of those ties and allow another person into your life 100% and create a new life then you are a liar and a thief. You are stealing the life of another person by your dishonesty.

Id he is a money hungry toad and wants the house because he does and he will let ANYONE he chooses live there and you don't have a choice or a vote ... he is a despot. And you my dear are a housekeeping bedwarmer.

Either way, make plans and move away. Get your own place. I doubt he will date you and will break it off and move someone else in pretty quickly. It will be tough at first but is your sanity and the ability to decide on your own future worth it? It is. Don't settle for a man who cannot commit to your happiness and impedes an adult from becoming the woman she can be. He is actually crippling both of you.

Looks like someone is now dating stepdown's exH.

He is not "caught" in the middle. He put himself there willingly. Meaning he moved farther from you (where a loving partner should be)and closer to the stepdaughter. If he is unwilling to be a supportive partner, I think you have an answer there.