I could help you improve your level of play but I don't think that would help. The issue isn't your level of play, it is tying performance to happiness.
Too many people make this mistake. When someone equates performance with pleasure they become result oriented and begin to resent all of the challenges on the table, because those are obstacles between them and the achievement they believe they need to be happy. Their quest to improve and earn happiness has made them miserable, frustrated and burned out.
Instead you can let that go and play to enjoy the challenge. When you play to have fun you win as soon as you put your cue stick together. The happiness isn't on the other side of a barrier we must cross. There is no barrier and no happiness anywhere but the here and now. Happiness can be found only with enjoying the challenges and difficulty of the game. When we learn to dissociate performance from enjoyment we can enjoy whatever the day brings. And the funny thing is that when we rekindle our childlike mindset where we enjoy the challenges the game brings, we tend to play better and our performance follows. Performance follows state of mind, state of mind shouldn't follow performance.
I thought about a time I raced with my kids. We were walking across the park and I shouted "I'll race you to that tree over there!" Immediately we began to run. Next thing you know there was laughter, my kids were shouting at me they were gaining on me, I fell down on purpose and they passed me, then I started gaining on them and they were shouting and running. What was the point of the race? To enjoy it for itself. What was at the tree? Was there some payoff? Some reward? Some "Look at me, I reached the tree, I'm so special"? No. The tree was pointless. It didn't matter. It was there to provide a stage for us to enjoy a race together.
Pool is no different. Yes we need goals and we should strive towards them, but if you hate the journey there is no payoff upon reaching those goals that makes up for years of misery, whereas if you enjoy the pursuit of those goals then you don't need to even reach them or waste time looking for some external payoff.
I speak about this a little in my link below. I am fueled by wonder and enthusiasm, I enjoy every session I put in, and my game has always followed. II wish all of you could experience the game how I do. So if you want to enjoy the game again I suggest you listen and feel free to PM me if you want to chat. Whichever way you go I wish you the best.