Panicking at the slightest hint of intimacy

I’ve been single for six years. My last boyfriend became injured in an accident and suffered brain damage. He became a completely different person. I stayed with him as long as I could but he kept lashing out at me in anger so eventually I left him. I guess I’ve never gotten over it. I try to go on dates periodically and at the slightest hint on intimacy I panic and want to run away.