Regrets and Depression

In 2013, I met a man who was the greatest help to me in a very tough situation. I was living with an abusive ex and was kicked out of my parents' house at 18. Me and him were very close and soon we desired to be closer than friends. He asked me out on March 2, and drove to Virginia (where I lived) and brought me to South Carolina with him. I didn't live with him but was adopted as my friend's mom's daughter and enjoyed life with him. After several months, he proposed to me and I was more than happy to say yes. After awhile, I started losing interest and began treating him poorly making him feel horrible. Eight months ago I decided to go to Kentucky for trade school and spent a last, beautiful and tearful night with him. That night I noticed that I had the best man in the world and I didn't appreciate what I had in front of me. I was willing to give up trade school despite my flight being in a few hours. He encouraged me to go. He Always cared about my well-being. A few days in trade school and I met another man who seemed to respect and consider me a lot. I was attracted to him but I tried to kill those feelings. Well this was going on, my Fiance was not calling for two days straight. I felt like he cared more about his job then me. I gotten overly emotional and treated him horrible even worse this time. He turned to drugs for his pain for three days and I didn't do anything but judge him. The last thing he's done for me was sing a song on the phone asking me to love him again.. but I ignored it.. and.. he dumped me. I was in pain.. I was so stupid I started dating the guy I met in trade school. But after awhile he started showing his true colors and I am now having regrets.. I want my ex back.. But he's now currently with one of my best friends and in the Air Force right now... I want him back... But I don't know what to do..Should I just let him go even though its hard or try to win him back? And if I do try to.. what if I am dissappointed in the end? I'm afraid.. I'm lonely.. I just want him back.. I was never happier than I was with him.. He was my soul mate.. And I just wasted a perfect relationship...

I'm already out of school. I got my certification as a Computer Service Technician. I have an apartment and making a good amount. About his girlfriend who is also my best friend of a good 5 years, she shows no interest in him. She cares more about an ex of hers who she constantly talks about. Honestly, I don't think you really read this thoroughly since you would know I am currently in a relationship now. I just needed to know what I should do in my CURRENT situation. Also it was more than a year that this happened.