You are falling back in love with your ex because you "recently got back in touch" with him. If you really don't want to be in a relationship or know it isn't right for you, you should really resist contact.
The contact was obviously too soon after the break up. You hadn't gotten over him yet. I suggest taking more time away from him. Is he reciprocating the feelings or are you just hoping? Have you gotten over the original or hurt from the break up yet?