its a coping mechanism. you get relief from cutting. so you feel more in control, and less overwhelmed. it also released endorphines (idk how to spell it). its a vicious cycle. but the relief is short lived. and in the end, the resulting feelings are worse than before, which is why you desparately try and cut more and then you hurt and then you cut, and it goes around and around.

why do you no longer see your t? if you are having sui thoughts all day, then that is a reason to stay in therapy. you wont be able to quit cutting until you solve the real issue underneath. and a therapist can help you do that.