Tao, you gotten some good advice and reassurances that you are a worthwhile human being and you have people who care about you.
I sincerely hope you are able to follow through with some of these things. Since you've no T to talk to, is there anyone IRL that you trust enough to share your feelings? What about one of the anonymous help lines?

Just my 2 cents worth, but I have found the following to be helpful to me...
Have you a safety net in place for these hard times? Are you able to generally spot when these feelings start creeping up on you?
You can design your own safety net, obviously, but here are some of the things that help me...
A. I have a couple of people that I trust to call me on my behavior. When they see me acting in the old way, they will confront me in a heartbeat. Nine times out of ten it does make me look at what is happening in my life that needs changing.
B. Sleep. When I'm sleep deprived, nothing--and I mean nothing--makes me feel decent but it will make me feel hopeless. I do my best to get adequate sleep even if it's power naps during the day.
C. Nutrition. If I cannot force myself to eat solid food, there are liquid supplements that will maintain your glucose level and most have some protein added also. Low blood sugar can be a very big reason for inertia, whether physically as in doing work or emotionally as in giving a damn about anything.
D. Relaxation. It doesn't have to be fancy; something that is yours alone that gives you some relief. Perhaps not joy-jumping relief, but enough to get through another hour.

Sound childish? Perhaps. Sometimes it's also the simple things that give us the gifts.
An hour at a time was too hard for me many times...I had to cut it down into ten minute increments. I was able to ride it out...

I do want to commend you on your honesty, Tao. You realize it's self destructive behaviors and you want to change them. That alone is a very big step...

Please talk to someone. Don't stuff your feelings...doing so tends to make them seem too hard to handle, and it also empowers you when you shed light on them.

My best wishes that you feel better soon,
Cap