How to handle contrition

I've hurt a beloved one a lot. I've done something which is unforgivable to this person and the contrition is eating me up. Contrition is, of course, a essential part in learning and preventing mistakes from beeing done multiple times. However, my regret is blocking me, I can't think about anything else. Has Buddha told us anything about this? Of course I have to, and already do, a dialoge with this person. However, how should I handle this within myself?