I don't want to move in with my best friend and his gf
Have you told your best friend that you don't want to move in?
I have told him a few times.
It does seem like you are doing the right thing by letting him know that you are not comfortable moving in. It is good so that the he knows ahead of time and can make alternate plans.
I knew it, I would never move in with my best friend and his gf.
Yeah, if you have problem with it you should not feel pressured or forced. Do you have other living arrangements set up yet?