My boyfriend always points out my flaws..?

I am 20 and he is 20 we have been together for two years. And he alwAys tells me how I need to loose weight .. I am 5'2 and weigh 128 pounds... I was a ballarrina for 16 years. I feel I loose my stiff body because I quit dance for a few years. I dated a guy for 3 years he was my first love in a lot of ways and of course 3 years later it went to ****... He was a jail boy that couldn't keep out. Then finally I felt these feelings to ky recent man whom I've been good friends with for a while... We started dating and 1 yeah later we started having problems... And about1 month ago he left be literally because I talked to a gay friend that he didn't know about, and I kissed my best best friend a kiss on the cheek in front of 19 people plus.... He left me and ****** his ex girlfriend from high-school and stArted talking about dating her... Then I find out from proof of his old phone that he had sex with a chick that was two hundred pounds.... No offense. He is 165 pounds. He dents it... What do I do ? I'm dating him again... About to be 20 year old. So confused.