is it bad i think i like my friend's ex

i have these 2 friends(J and A) that ive watched go from friends to lovers to strangers and ive been helping them out with their relationship troubles or whatever. theyre good friends to me and i equally cherish them but lately A has been texting me constantly for days and i text back js as much cuz like i said we're friends. we stay up past midnight, talking abt random things and i dunno when he told me he's never told anyone the things he's told me i felt a little special, when he asked me to keep talking abt my interests i felt butterflies. i know its wrong given his past with my friend. they only went out for a month and J realized shes a lesbian and ended the relationship. idk what to do... i dont wanna have feelings for him. or maybe these feelings are js excitement from having someone to talk to or whatever i dunno anymore. i dont think he'd like me tho.. i dont think he likes boys like me.