I’ve been online dating someone for a year now.
That aside, in 2011 when I was 16, I’d started online dating my ex. In 2013, the day I turned 18, I dropped out of school and bought a bus ticket to where he lived. It was great at first, but declined quickly as soon as trouble arose. For whatever reason, I’d stuck around for a few years after and only moved out and back in with my dad June of this year. I did love my ex, and I was sad to leave, but there was so much bitterness nothing could be done.
Back to my current LDR, I do deeply love this boy. However, I cry a lot since leaving my ex’s place, and every time I talk to him (which isn’t often, but sometimes he lets me know, because we did have a life together).
I’ve been tempted, thinking if my current LDR fails, maybe me and my ex can try again. Everyone I know hates my ex, for good reason, but I still find myself missing him and seeing him as my best friend. He never lies to me like he used to when we dated, something that was already changing before I moved out, and he’s losing interest in flings (main issue was ‘cheating’, him getting in fake relationships with multiple girls at a time online while dating me just to get their nudes/company).
I’m wondering if it would be possible for it to work a year or two from now? Both of us messed up in the relationship, and both of us have changed through the years, and I believe after some more time things will have cooled down enough for us not to fall back into old habits.
And secondarily, if my current LDR doesn’t fail, I’d still like to keep my ex as a close friend. Is this a terrible idea?
LemonVibe 
Yes, this is a terrible idea. You deserve better. Move on.
The problem here is your definition of “online dating.” Online dating is when people meet online, and then meet up in real life soon after, so they can see if they’re actually compatible with each other. Because relationships do in fact need to occur in the real life.
What you’re doing isn’t online dating. It’s building virtual relationships — that is, non-real relationships.
My suggestion is to put some effort into meeting people in real life, rather than escaping from real life by establishing virtual relationships. If you do end up meeting someone online, great. Just make every effort to meet in real life as soon as possible, so you can see him for who he actually is, not for the fantasy you’ve built up inside your head.
And definitely don’t drag it out for two years before meeting someone in real life for the first time, because by then, you’ve already formed an attachment, and it will be much harder to break it off if does turn out that he’s not a good match for you.
I’d say to break it off with your current virtual relationship, and sure, consider getting back together with your ex if you’re really that attached to him still. But I bet if you made a sincere effort to meet people in real life, you’d give yourself better odds of meeting someone who’s actually good for you.
If your current LDR is making you wonder about your ex and getting back with them, you need to leave your current one. It is not fair to them or you to string them along. Secondly, you need to talk this out with your ex, he did a lot of bad things to hurt you like cheating. Personally, I would not give him another chance to hurt you again.