What are the best ways for learning how to not become demoralized?

[Hardkill]

If I fail at something once or even few times, then that's not a big deal to me.

but I often get easily discouraged or feel hopeless when things aren't going the way I had hoped after constant failure, particularly when I truly tried my very hardest at something.

I either have a meltdown or get very depressed or feel hopeless or pessimistic or become nihilistic or feel suicidal when this happens.

I've tried visualization before but unfortunately it only made me feel even more disappointed and shocked every time something didn't turn out the way that I expected or hoped it would.

It's now as if every time I fail at something I am like "I guess I really deluded myself into thinking that this really would workout.....What was I thinking?......I feel really stupid and embarrassed with myself."

If any of you here know what are really the most effective methods to really learning not to feel the pain of despair after constant failure I would appreciate it.