i am sorry to hear of all this. i know you love him and want to support him, but his back and forth with you and constant break ups show that at this time he may not be capable of more. if you love him and want to take him back each time that is up to you. keep reassuring him you are there for him always. he is dealing with a lot and he maybe smokes pot to escape and yes can contribute to ups and downs. give him space when he needs it and be there when he needs it as long as that cycle works for you.