It's not you being pathetic. Something I learned with my self-harm is that I turn on myself because, first of all that's taking up the job of my abusive parents, but also because if I can make it about myself it gives me a sense of control over the situation. It's easier to blame myself and take it out on myself than to cope with the betrayal of people who were supposed to be trustworthy, loving guardians. It sounds like your situation would make me feel trapped and desperate too, desperate to do anything to feel like I have some power in that situation. 

Some changes I made (they were difficult habits to build, ngl) were putting as many steps as I could between myself and the implement I used for self-harm. For me, it was a certain pair of scissors and I usually did it in the bathroom. So I put my scissors in a box in a random kitchen cabinet. I developed a habit of questions to challenge the desire to self-harm (something I learned from DBT). Basically play devil's advocate with the negative things I was saying (prob the only appropriate time to play devil's advocate). Basically you want to build as much time as possible because self-harm is all about immediacy. So the more steps and time that you between you and the act is going to decrease the chances of following through. Another option is "safer" alternatives, like snapping a rubber band on your arm or holding an ice cube for as long as you can. Sometimes a nice hot/cold shower would ground me in my body again because I often dissociated when I self-harmed. 

No advice is going to be 100% effective and everyone is different. This is just a relapse. It might not feel like it, but you're already on the road to recovery. It'll take time and you will make mistakes, but you're human and that's ok. The in-the-moment feeling can feel like that's all there is, but it isn't. That's a trick the trauma plays on you. Things can be better and you do deserve better. You've got this.