What should i do w ma b/f and ex?

okay so ive been w my bf for almost 2 years....and am falling for my 2 yr ex...im trying to ignore the feelings i have with my ex....but i cant. I want him because we didnt leave on bad terms....he moved...But it seems like now im noticin stuff about my bf....it seems like all he thinks about is sex...i no hes a guy...but still....today me an m ex were talkin an i was jokin askin him would he still like/want me if i gained 400lbs an got really dark an had a deep ghetto girl voice lol...an he said yea cuz it wouldnt change how i am on tha inside.....so then i ask my boyfrend would he leave me...an he straight out said yea!...like dam....antha other day he told me i was gettin fat....so now its like if i gain a few more lbs he could leave me!...he thinks i was jokin we i asked...but i wanted to no what he would say....evreytime im w my bf lately i wanna just hurry up an go home so i can call my ex....even wen were makin loe...im thikin bout my ex....Should i stay w him?? or get w my ex??or what?What should i do w ma b/f and ex?
.He's into your pants and letting you know he'll dump you at the first opportunity.At least he's honest.Now your ex,he tells you what you want to hear.He's not stupid,he might want some too