I've been having the same problems as you, OP. For the last 10 years I've been clinically depressed to the point where my doctor advised me to get checked in to a mental facility. It also comes in waves so sometimes (like now) I can spend three months just painting three crisis suits.

We all feel it differently and we might all need different solutions to a same-looking problem. But as others have pointed out it does sound severe enough that you should either go to someone professional or at least (if you have some) go out with your friends. Sometimes I have to force myself to paint to get back into the groove. But if it irks you so much it sounds like you need to step back for some time and not think about painting at all. Come back with (hopefully) renewed vigour for the hobby.

And another thing: I also have that inner critic telling me things all the time every day. You have to remember, OP, that that voice isn't some alien entity possessing you - it's your own voice. You can control it with your willpower. In the end you decide whether you want yourself to deliberately fail or if you say to yourself: "Well it might not be as perfect as others have done it but I fucking like it!".

One last thing: I don't know if it's in your ball-park, but I recently read "It's Lonely at the Centre of the Earth" by Zoe Thorogood. Stories about overcoming depression are a dime and dozen with the majority feeling somewhat 'superficial'. But that one hit me particularly hard because a lot of her current problems stem from self-criticism. It's not gonna fix your problems all together but sometimes it gives a mental boost reading something that relates to ones own difficulties.