You have rights and your rights will be recognized in court, so it doesn't matter what he thinks or wants. He is in la la land/limerence or whatever it is. He left to go live in another state which is somehow going to help you to gain hopefully full custody of your sons.
May be he needs to go live his "dream life" to realize after a while what he lost, reality is going to hit him in a few weeks or months, by being away from you he won't be able to blame you anymore for whatever is going wrong in his life.

Take care of yourself, finish your studies and find peace.

Me 52+ WH 57+
Married 20 +
Piecing since 2016 (ready to give up...)