Hi there. I am so sorry that you and your son are dealing with such complex issues at present. Please make sure that you alsosee your gp for support as you need to be as well as posible to support your son. You did the right thing in dealing with the wound quickly and it is also important not to make a big deal of any deliberate self harm that may happen in the future - it needs to be dealt with practically and dispassionately so that he does not associate harming with positive attention. Also, bio oil is a great product that will help to minimise any scarring.....you can get this from most chemists or online.
Keeping him safe is also a priority - if it happens again, make sure he sees his gp/mental health team/key worker for assessment as soon as possible. Do not be afraid to call the police if you arebunable to stop him harming or he needs to be safe. I have done this for my hubby countless times and all you can do is offer to be there for him. Take him to appointments, offer to go in with him and listen as quietly but as attentively as you can. Let him know he is loved often, and talk openly with the health professionals you are seeing - do not be tempted to hide things from them on his behalf.....this is hard because sometimes they may ask you to do this, but it is not the right thing to do.
In respect of the criminal aspect of things, ask the police for referral to victim suport and the officer in charge of the case should be liaising with you and your son closely. It seems like court/criminal proceedings drag on frever, but it will get there. It sounds like you are doing all the right things, and all in your power as a mother. If you require any more specific advice, we can get in touch by email and talk about things more privately if you wish.
Good luck and do take care of yourself - you need to be strong and solid for your son......and things will get better. The journey is just really hard work. Lisa x