First off, congrats on 4 months! That's a long time.
Relapse is apart of recovery. We all do it, and it's going to happen. You are not worthless! You are just going through a rough patch, and you will get through this. Do you talk to a counselor or therapist? If not, I'd say maybe check into one. As they say, fall down 6 times, get up 7. Keep going! And stay strong.
If you ever need anybody to talk to, you can surely
PM me.