<human>: Give me the gist of the text in a nutshell

While this might get down voted because of my actions so be it, I wrote this out because I've put two people through pain (one more than the other) and I guess I'm looking for advice just now,not necessarily on the situation but just on how to be a less shitty person in the future.

What I did, Dating a girl (Anna) a couple of years younger than me, I fell for someone else (Bell), Scared of being the Devils advocate I kept quiet about the situation. Trying to just be friends with Bell (who knew about Anna), for a few weeks worked, but one night we slept together while drunk (not an excuse I know).

It didn't happen again, and after 3/4 weeks during which Bell decided she didn't wish to speak to me anymore for not telling Anna I decided I should. After realizing that while I didn't want to be the guy that fell for someone else i was, and that I had to face that. To this day I'm not sure of that decision. I could have kept my mouth shut and rode this out (I'm moving cities in a month, and its been long established with Anna that our relationship would stop then). Obviously it didn't go well, who wants to be someones 2nd choice, while your supposedly dating them?

Now, the situation is on her own Anna decided to keep us going until I move away, She made that decision on her own without my guilttripping her, based on the decision we could still have fun and she'd be able to overlook what happened, we do still have fun together but its basically a dice game of trigger like things that will remind her. Its going to be an up/down ride to the end and looking back (Hindsight is always 20/20) maybe i should have ever said anything, or maybe i shouldn't have let her get back with me, for her own sake?
   
Its a pretty closed path from here on due to my leaving, but when I do move, I never want to put another human through this pain again. Reddit, what can I do?
<bot>: I'm a dickhead, I've caused horrible pain for two people, I dont want to hurt anyone again after this, help?