It sounds to me like you are very depressed! I'm wondering if an antidepressant would work. Have you ever been on any?
Since you don't want to see a therapist, why not talk to your doctor about anti-depressants? The chemicals in your brain might be messed up, and the anti-depressants correct that and make things feel more "normal" so we don't have those horrible lows or highs --- in your case the horrible lows.

I think it would be worth talking to your doctor about it.
Why not give it a try? I hate to think of you living like this.

I remember when I too felt like that, and it was awful! I've been on anti-depressants now for about 40 years! I have clinical depression, and I'll probably be on them til the day i die.
I wish you the very best my friend. Please keep us informed. God bless and take care. Hugs, Lee