We can't really understand because we are not you. Many of us have been through something like this though. I went through some very tough times with my former wife. It was extremely difficult.
We can't know all that you are going through, but we can and will pray for you. Although this situation is painful...you can make it through this. As Kara said...God has a plan and a purpose for you. There is only one you, and only you can do what He has in store for you. Spend time in prayer each day, and His word. This can and will benifit you. Remember that God loves you...every day, no matter what has happened or will happen. You can always count on Him to be there...always.