Katrina,
Welcome to SR, I am so very sorry for what you are going through. Meth is a nasty drug, I know they all are, but my main expierence with my ex was his meth use, and also with my brother as well. I asked all the questions you did, why why why..... I have found that I will never really get those anawers. So I had to turn my attention around to myself and my son. I had to start taking care of us. It will be tough at times, no lie there, but take things one day at a time, one minute at a time if you have to. Keep coming back, read and post. We are here for you....