It is perfectly normal to feel how you are @Spike, you aren't alone. I had a major mental health wobble a few years ago (when I left the forum) and sadly followed that up with another wobble a month or so ago, to the point where I'm speaking with a therapist as I was very close to pushing the suicide button. As bad as telling my wife that I didn't want to be around anymore, something which absolutely haunts me.
There is a mental health crisis at the moment, due to lockdowns etc but to be honest the stigma has meant that it's never been talked about. People opening up like you have is a small step onto the right path, I don't have any magic words of wisdom but I'd stress you to speak to someone and get things off your chest in a professional setting and give yourself the comfort that there's thousands (probably millions) of people that feel just like you do.
My PM's are always open mate, please speak to me if you ever want to x