It sounds like you've had a rough time lately, so please do the nicest thing you can do for yourself and stay sober. Being under the influence is not going to help you deal with your parents. It will make things worse. You need to keep a clear head to keep the situation manageable for yourself. My sobriety is also being somewhat challenged by one of the people I live with. I tell myself that my first and only priority is to stay sober and that no matter what this person does, I can choose not to react to it. That doesn't mean I won't deal with it eventually, but it does mean I can put some distance between whatever he does and how I choose to respond. On a couple of occasions, it has meant not responding at all, literally, just ignoring the behavior.
So for the time being, give yourself a break, and forget about confronting them or writing them letters - just take care of yourself. You'll find lots of support here.