Wisper, hun, first off, you're not crazy! you're very normal. what you're going through a lot of us face, but i know that does not make it easier for you.
i know this will sound harsh, but i think you should let him go. hear me out. he had feelings for her when you got together, he's considering letting her move in, knowing that 'something' may happen. he does not sound committed, or ready to commit, to you. as yet. maybe in the next few months things will change. maybe not. life isn't easy.
i know it's hard, but the only other option i can see is to go with him, and maybe fight for him. but you have to believe he wants you. if not, it's a losing battle.
you have my prayers.

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I wouldn't say that I'm always horny... it may be true, mind you, I just wouldn't say it!