First off, this all starts with self love. People come and go in our lives all the time, you are the only consist person in your life. That will never change.
So once you give yourself a chance, and really be comfortable with who you are, the rest will fall into place.
I'm finally at a place in life where I could less about others opinions of me. Because at the end of the day, mine is the only one that matters.

Second, set goals for yourself. They can be small or even huge. Start setting up steps that will help you achieve those goals.
Some of mine are to live a healthy lifestyle, go to the gym regularly, take a few risks, and graduate with my masters in architecture. Now these are totally attainable even though I struggle with my confidence in that sometimes. But I have a great support system that helps me push myself.

Third, once you've done those things, really enjoy yourself, your life, and your decisions. You are going to reach a point in your life where you realize how happy you are. But don't think for a second that you won't have rough days. That's just unrealistic. There will be plenty of those. But with a little guidance, faith in yourself, and a good push, you'll make it through. I promise.

Best of luck to you and your happiness!