I ghosted my gf because she was fat.
What was your problem with her gaining weight?
After she got fat I couldn't handle seeing her anymore.
If you're not attracted to your girlfriend anymore, for whatever reason, you are certainly entitled to break up with her, but ghosting her is the wrong way to do it. Relationships are built on communication, so talk to her and at least let her know that it's over, so that you can leave on some common ground.
It's really difficult to talk to a person like that who has let themselves go. I am not saying a word to her.
Walking away from your gf just because she gained weight and not saying a word to her is inconsiderate. Be courageous and at least tell her why you did it so you both can get some closure.