You shared about endless cycles of depression for four years. Have you tried to talk about it to someone or tried seeking help? You can share about it to the Experts in this Platform as well. talking to a Counselor or Psychologist will give you more clarity and can help you to handle it better as well.
And regarding your mother, maybe her intention was just to stop you from doing that. But yes, maybe she couldn't do it properly. And yes, maybe the way she chose was not fair, and definitely didn't help you at all. Why not try talking to your mother openly about it and try to know the actual purpose behind what she said. Maybe she doesn't resent you for cutting and is just concerned about you. But maybe she has not been able to convey that to properly. Your anger or feeling bad is very natural, just try to think in this perspective too.
As you said she is the only parent in your life, so there's quite possible she might be going through a lot as well. Try to sit with her and encourage her to share, express to her how her way of dealing with things is not helping you actually. And how you would really want her to support you.
Who knows, maybe that could help!