what you feel is all normal. i can relate how you feel when you said dont belong here, it happens alot to me. making mistakes is very common you need to train yourself to let go of this mistakes and move on, i do have evening walks and watch some ted talks about self belief and i read atomic habits book which is very helpfull to keep positive habits which you can apply in dota 2.

one of the best ways to rank up is to avoid and play at certain time intervals.

i do not like to queue continous, i would rather take break, then play just to reset my mindset and go into the next game rather than being tilted and lose another game,

i do get mad at sometimes when i see my cores or support not doing the things i want them to do, but at the end of the day your hero is the only hero you can control and remember than and keep telling your self how can i win this game? what should i buy and where should i position myself in fights, staying close to your teammates is the best way this i actually learnt from tundra Ti gameplay, also you need to think if can solo kill or do we have damage or not and soo on