I support everything the men above write. You seem to be dealing with a lot of self-doubt, questioning your judgements, desires, what is ''right'' what is ''wrong''... and probably lashing yourself silly for any choices you make. Is that close to your experience? I can totally relate. Would you like to move beyond blame and self-loathing, or is it somehow familiar, and protective in nature. Does it serve you to hate yourself so? I wonder...
Can you allow yourself to see life as a great experiment? Can you try to give yourself whatever is so forbidden or ''bad'' in a way that you objectively know doesn't hurt anyone, including yourself? For example, can you allow yourself to imagine and feel that deisre to hurt yourself, breathing through it, situated in a safe space, without picking up something sharp and actually doing harm to your body? If you get overwhelmed and choose to hurt yourself again, can you notice what brought you there again?
My suggestions come from personal experience and professional advice, but may or may not work for you. I overcome a painful over-eating and starving cycles, with tonnes of shame, by eating precicisely the food I had forbid myself, (which when I consciously chose to eat, and noticed how I was using that to cover over fears, I actually didn't need to binge on. Recently, I applied this crazy wisdom to the strong sexual urges I have been having towards men and which paralyzed me with fear and so I would cut them off. When I allowed myself to feel the desire, it became increasingly violent towards other men, then my dad (who sexually coerced me and betrayed my trust as a child) and even myself as a child... I allowed myself to sit with and feel fully the deisre to do what was done to me, the surge of helplessness and that intense yet false sense of power (power over) flushed through my body. Now I feel much safer, in myself, and around men, and kids.
Courage, Liam, courage! You are not alone. We all walk with you here. If you need support, I encourage a good therapist, of your choosing, writing to this board, and a tool for emotional self-support (such as http://www.emofree.com).
All my love to you as you pass through these storms.