I feel like im half drowning in my relationship

Its a new relationship we both jumped into and recently hes started using crystal. It makes him a different person. When hes on it he is an evil person you can see the hate in his face. But the last few days weve been back to normal cause he hasnt used but when its coming out of his system hes very on edge and i feel like i cant even say something or touch him without him flipping out or rejecting me and im terrified of rejection by people i love and care for. People tell me to get out of the relationship but i feel in my heart he needs someone thats a positive influence on him to keep him away from that stuff. Ive never been with someoone who uses so this. Is so new to me idk what to do