Just stop giving a fuck what everybody thinks about you.
In most cases, the majority don't actually care anyways.
People have their own lives to lead.

Start with your looks. This is the easiest for you to change. Join a gym. Start looking good. Buy nicer clothes. Style yourself so that you look in a mirror and think, Yea I'd fuck that!

At the same time, talk to your girl. But answer this question for us, DO YOU WANT TO STAY WITH HER?

If you do, cut out all the PUA stuff and fix the relationship.