Improving myself and getting rid of my bad player habits

Title really says it all. For a period of time (one or two years? Hard to tell) I became oddly ill. Incredibly sleepy, irritable, forgetful and it was all I could do to participate in the game. The GM thought I was becoming apathetic to his world, the other players just assumed my character was being distant, and I struggled to roleplay and deal with some mechanical problems with the character and the system (lots of homebrew) as a whole. However, with medication, I slowly started coming around. This came at a cost, however.

My irritability became explosive. I said things that I regret to this day, and ruined some friendships as a result. Its been… almost 9 months since the last straw was broken and the long running game had to be put on hiatus. We had thought to try and talk things out, see if we couldn’t cement some positive habits in place of negative habits through a series of modules, each run by a different player, and then being run by a GM. Unfortunately, my schedule went haywire and this couldn’t happen. I decided to back out of the group until I could fix myself and so they could continue playing in other games.

Lately, I’ve noticed myself falling into bad habits. Lots of negativity toward certain mechanics or just some darker thoughts. Nothing to talk with a psychiatrist about, but more things that I’m trying to fix about myself and get rid of.

I’m wondering if anyone knows of a good way to help change the way a player plays without them being in a game? My schedule doesn’t allow me to play locally, and I don’t want to subject a gm to me if I relapse.

EDIT: Sorry if the tags weren’t correct. This is a difficult question for me to figure out.