*I need help*

So I’ve been talking to this guy(carter) and I really like him and I could see things moving forward into a relationship. However, I still have a little bit of feeling for this guy(Justin) that I’ve known forever. Justin knows I have feelings for him but isn’t ready for a relationship since he was just cheated on. Is it wrong for me to start dating Carter if I still kinda have feelings for Justin.(and honestly, I’ve known Justin so long that I don’t really see us dating, maybe it’s just sexual attraction since we have done ‘stuff’ in the past idk) but I would be going all in with Justin, he’s not just a place holder or anything like that. Thoughts....?