Some people would read this and go "Well, life isn't fair, suck it up", or blame you somehow. For a moment, I felt inclined to say the first, minus the suck-it-up. I mean, what else is there as an explanation.

I don't have any similar experience, but for whatever reason, I feel for you. The anger, the impotent frustration - especially if you were wronged by this person.

You say you have vengeful thoughts - maybe try to convert those into motivation to wor harder on recovery, or to find something you're just as passionate about? I'm not saying that's easy - gods know, I sit here in my room seething with envy of just about everyone with zero motivation of my own - but it could be a possibility.