Well, I've never lost sleep over losing at anything. But I can empathize with your discomfort over losing a very close match. I've blown more set and match points than you can shake a stick at.
You probably just tightened up a bit on those set points because you really wanted and were really trying to win. That's not a bad thing. Happens to everybody from time to time. Hey, that's what makes competition fun and interesting, and challenging.
Hopefully you're a better and wiser player because of your experience, both winning and losing.
If you can meet with Triumph and Disaster
And treat those two imposters just the same
If you can make one heap of all your winnings
And risk it on one turn of pitch-and-toss,
And lose, and start again at your beginnings
And never breath a word about your loss.
Don't worry about the past. It doesn't exist any more. But remember it, because it's what we learn and grow from.