Yep. Dont agree to therapy OP. Your partner will only use the therapist to further undermine your self confidence, and gaslight you (interrupt you, minimize your feelings, invalidate you by calling you a liar).

Think of therapy with your partner like you are agreeing to willingly be led into a closed and locked cage with a wild animal (your abusive partner), with no weapons (self esteem, emotional boundaries, abuse evidence) to use for self defense.

He will make you out to be the mentally ill person, to take the focus off of himself so that the therapist diagnoses you and medicates you. Not him. Then, he wins.

Just stay away from him. Grieve the six years and heal and start over.