If you really feel like it is something you'll regret doing for the rest of your life, then the most logical thing to do would be to do the thing that will keep you from that regret, right? So I ya wanna know for sure if he still wants to be with you, then don't be afraid to take that step out there and just ask him. If he says no, then you just gotta move on...but think bout if he says yes. Then you would've made a big mistake if youd never tried in the first place
Tell him you love him. If he doesn't take you back explain it. If he doesn't then he wasn't worthy of you. But try to get him back. Just explain you were scared. If you get him back never let him go again.