You have to take things at your own pace. I can completely understand why hearing him call you his "roomate" is hurtful and perhaps he is saying it in front of you to hurt you.
When you feel ready of course you can start dating. Do not let him decide who you should and should not be with. I personally have to give you credit for being willing to live with a guy that you dated. I could not do it without being an emotional wreck. Have you thought of moving out? It could be very difficult to move on when you see this person all the time...Just a thought...
Unfortunately there is no blueprint of how things should go now. If he wants you to be his roomate then act like it. Do not give him the satisfaction of showing that you are upset. Especially if he is not being supportive.
I wish you the best and we are here for you.

Jessica