I haven't seen your other posts, but part of your current post speaks for itself.
Regardless of how bad things are right now for you, harming yourself is only going to complicate your situation and make things worse. At best, if you can call it that, you may have a short period of relief, but it never lasts and then you are left with the guilt and scars.

If the relationship that you are in right now is important to you, see if you can both get a counselling session together. Even if the problem isn't with the relationship itself, it will help you and your partner understand why you have the urge to punish yourself. Having someone else in authority explain to a partner about a behavior that can be difficult to understand is often better excepted than it is coming from the person with the behavior. (Hope that makes sense). Also, once that is cleared up, both of you can work on getting through the urge to self injure.

Most importantly, don't give up. You are obviously important to someone and that is a good thing. You don't deserve to suffer and there is no reason why you should have to. Self injury isn't an easy fix, but with the support of your partner and a good therapist, you can make it through.

Sam2