Well you came to the right place. We are all in some version of the same boat.
When Divorce remedy gets here, read it. Then read it again.
To summarize:
You moved out to Cali to pursue the art thing and she thought she could support you while you did it, but realized she could not. Now she has found someone who is attractive to her (because she has not supported him for the past 3 years) and she wants to bail. You want her back, but (from your telling) the main thing that drove you apart was you neglecting her for your studies.
Do you want to begin neglecting your studies for her? Do you want to give up your dream of a new career to chase her? How will you feel if you drop out of school, give up on your dream, and then have to work a job you don't want just to have her?
Things to think about.
In the meantime, distance yourself from her and quit chasing. Figure out the things about yourself that need to change to make you better (not for her). She agreed to hold off on the divorce, then told you she felt pressured. Listen to her. You will have to decide where your boundaries are with the other guy.
Others will be around soon to offer plenty of advice. Read.
Me 36 W 40 S 13, 9, 7 ILYBNILWY 2-08 Discovered EA 3-08 Reconciled 7-08 She says she's been faking it 11-09 She wants to separate 12-09