I'm going to cheat on my psycho gf
Why do you want to cheat on her?
I wish to find someone better, someone more understanding
If you are not happy with the relationship, you should just break up first before you go around cheating. If you cheat on her now, you will open a can of psycho worms that you wish you didn't open.
I feel like I have no choice.
You definitely do have a choice. Just tell her it's over and then you can go be with anyone you want.