I don't know if there's anything at this point. Maybe a time machine? I've hated my life, and have had suicidal thoughts since I was a very small child. But there was a brief moment of my life where I felt like I might have a little hope for a happier future. In 2012 I got into a relationship with a girl I absolutely adored in every way; I loved her personality, I loved her sense of humor, the things she was interested in, the way she thought... not to mention, I thought she was absolutely gorgeous and have never seen another girl in person or otherwise so perfectly tailored to my preferences when it comes to what I find sexually attractive in a woman. She convinced me that she was pregnant with my child, and I genuinely believed her when she told me how much she loved me and the prospect of building our life together. During that little window, I actually saw my future with our little family and believed I could be as happy as I've always dreamed of one day. Unfortunately, it turned out that she was lying about being pregnant. She faked a pregnancy test I bought by having a friend pee on the stick from behind a shower curtain while I waited for her outside the bathroom. I could have lived with that, but I didn't find out until after I'd already discovered she was cheating on me. A lot. There was four guys I found out she was fucking who were just old fuck buddies she'd been with off and on I guess. Then there was another guy she was fucking in another state who was her boyfriend before me, having convinced him of all the same shit. Then there was ANOTHER guy she started fucking after we got together who was her "boyfriend," too. And, to top it all off, there were at least three guys who fucked her during their stay at the hotel she worked the front desk at- that is, three that I outright found the messages confirming they'd fucked. There were four other guys she'd been messaging since they left the hotel that had stayed there and met her during our relationship, but they never outright talked about having fucked- despite how blatantly obvious it was that they did.
Regardless, I can honestly say that my depression and suicidal ideation isn't because of that experience. It kinda sucks that it had to be my literal dream girl that hurt me SO bad out of all my failed relationships- but I was pretty much just as miserable now as I was before I met her. I mean, I was still suicidal and had tried to kill myself plenty of times. But I can definitely say that I hate how I still love her to death despite how fucking terrible she did me, and I've never been able to love another girl since in the same way because they never click with me so perfectly. But I guess, to answer the question, if I could hypothetically build a mind-erasing time machine and go back to that brief period of a few weeks where I was blissfully ignorant to her seeming hate for me and genuinely believed I had a child on the way with my soul mate... Then, yeah- I guess I'd have a pretty decent shot at being happy if I could use it to erase my memories and live that little loop over and over.