I need help.
If he wanted her to be gone, she would be gone.
She moved in without him asking?
I'm sorry to sound harsh, but have you ever considered finding someone who has better judgment? Who doesn't rush into love (he loves you "and always will" after what, two and a half months? seriously?)
He is absolutely right, he can't give you what you need. I know you dont' want to look at it this way because you have strong feelings for him, but you are dodging a bullet by being broken up with.
You're not meant to be together. Being in love with someone doesn't entitle you to a relationship with them for the rest of your life, nor does it mean that a relationship with them will be a good one. Start thinking with your brain, and put your emotions aside. You really need to be more realistic about the situation you are in. Being heartbroken is sometimes preventable. When I read your post, I am reading the words of a girl who is making herself a slave to love instead of treating herself with respect.
It doesn't really make sense to me that he would have to "take a break" from dating you just because a rommate that he supposedly doesn't want living in his place moved back in.