Me(25M) somewhat cheated on long distance GF(28F) of 5 years and regret the hell out of it.

Cheating is cheating, I get that, and I know saying "somewhat" is stretching that boundary, so I'll explain. Her and I have been dating for 5 years online which is ridiculous I know. I've been finishing college while working full-time and we talk all the time and even sleep on the phone together every day. It's amazing, beautiful, and honestly I couldn't imagine myself being without her. Her and I have met once and it was absolutely amazing, however I wasn't at a comfortable stage to have her move in. Thing is, I've been pretty lonely physically. I'll have girls flirt, let her know about it, and always disengage.

Anyways, our boundaries were that we'd only really talk to each other alone, since that's kind of all we have with each other. Which if you think about it, makes sense. I screwed up the past weeks though, and there's no excuse, nor can I forgive myself. I've been talking with a girl near me from time to time, and though I've shrugged off sex, I'm still emotionally cheating in a sense. Needless to say, I blocked the girl, especially once I remembered how little I relate to others compared to my gf, but now I feel like complete loser for even doing something so low and shady to such an amazing girl.

As much as I hate to admit it, not having sex messes with my head, and over the phone gets old. And though I wasn't doing anything physically with the other girl near me, the fact that we had hung out together before made it more interesting, and it was also a change. I've only had sex once my entire life, but before this I used to circle around girls to talk with faking my personality as I just couldn't relate. This instance kind of brought back those memories and as mentioned before helped me remember why I'm in love with the gf I have in the first place.

So I guess what I'm asking is, what should I do? Tell her? I feel like logically I should wait until her and I meet, make her comfortable, and then admit it to her- however at the same time, that's also obviously very, very shitty and manipulative. Her and I are finally so close to being together, and unfortunately the stress has made things pretty rough- in a sense we're almost like a married couple and we've only met once.