I think I might still have feelings for my ex… :(

So, I (F27) have been with my current bf (M24) since last summer, after I before that, broke up with my ex (M26). However, I recently started talking to my ex again (he lives in Canada and I’m in the US) and we still seem to both have feelings for each other… But, I do care about my bf (M24) too. He’s sweet, kind and treats me really well. I’ve known my ex (M26) since 2010. He’s basically my best friend and the person who seems to know me best. My question is, what should I do? Should I stay with my bf (M24) or should I break up with him and do LDR again with my ex bf (M26)?