How to start this. I think there are a lot of underlying issues with what I have read and this is only an outside perspective. Some other commenters have already said similar things but here we go. Take this all with a grain of salt and ponder if any of this fits. It is not an attack but my observations and experiences from a cruel world.

First thing I would like to point out is you seem to have a need to gain happiness from others. By this I mean you saying your life hasn't gotten any better, hopelessness, how great this person is and they greatly improved your life, etc to me sounds like you have some deeper issues with yourself. You are broken in the mind somewhere or perhaps an empath where you can't help but rely on others for emotional balance. Where ever that stems from I feel like it may be eating away at your perception of everything around you. This is the first thing you need to correct in your mind before you will ever find happiness with another person. There is no one nor just one right way for people to find who they are. Many are never put in the position to figure that out. But alas it should be something you strive for. Much more to say on this matter because if is important but the night is late so I'll continue. I see this in your comments because you can't let the past go and enjoy the good experiences you gained from it. You are accusing yourself of "not being good enough" for this gentleman. You are comparing yourself to his friends. You've then compared your entire life to not "improving" from something three years ago. That one is is the worst mental shackle you can put on yourself. You say "don't throw me a pity party" but that is the whole post. Why do you dedicate so much of your mental capacity to constantly tell yourself horrible things? Silly humans and emotions. What are you doing to try to improve your situation?

Second part I would like to touch on is has already been covered by others but you sound incredible naive when it comes to dealing with people. There are all times of people out there. Majority of people are good and mean well most of the time but we all carry inherent bad traits. It is on the person to recognize and learn to live a good life with those traits. But you can't rely on people always being good to you because that isn't the world we live in. You need to develop critical thinking when dealing with other people. For example everyone has a motive. What is their motive when interacting with you? It can be good or it could be bad. Narcissistic people are a great example of the type of person that uses emotion or some other form of leverage to turn situations in their favor. But there is just a drop in the river of what kind of people are out there. No individual is limited in their capacity either. You can meet someone that is a master manipulator but only does good with their abilities. The old neighbor that always shows up to help, gives you the best advice, or just makes you happy when you are down. The world isn't black and white though. If you don't have a natural talent to identify people and their motives there are plenty of self help books, videos, and therapist you can gather the knowledge from. The kicker is you never stop learning and identifying new types of individuals. To me it is beautiful to see the diversity that is our species. Learn to see things differently than you do now.

Last part for this evening is learning that sometimes the right thing isn't. Just because we desire or feel something so completely it feels like a missing piece of yourself, doesn't mean it will work out. You may never have another relationship that completes you as much as that gentleman but I say that is pure folly. You've limited yourself to never having room for improvement and it will negatively affect all future judgements you make like shooting yourself in the foot before the race starts. We have to play by the universe's whims and not being able to let go of something will destroy your mind. For context I ended a relationship with what in my mind is the greatest woman for me. But life had other plans. I remember the bad and good but try my best to dwell on the good. Makes me happy to remember her love for baking. I miss her and wish it had turned out different. It would also be extremely unfair to previous and future relationships though to say no one else can compete. All relationships have ups and downs, it really just comes down to how much energy the other person can put into making it work. Also communication. But that is a whole book that would need to be written.

To sum up my rant now that I'm looking back at this wall of text. Get out of the pity party pool, pull your big girl pants up and educate yourself on yourself as well as how to deal with other flesh bags I mean humans. You did good reaching out to others though. That is the first step no matter how small it may seem. Pat yourself on the back just keep trying if even a little. The universe if unforgiving but there are a lot of people willing to help. Chin up you'll make it through.