Julie -- stop. You can "what if" until the cows come home. You can't do more than you are doing. I have been in a similar- yet different - situation with my son. I felt all his acting out (drugs alcohol and trouble with the law) was my fault. "If only" I had done... something and I had a long list of 'somethings', then he would not have done what he did. It took some counseling to realize there was nothing I could have done. His behaviors were his decision.
Get counseling... for both of you if you wish, but defnitely for yourself. It could open your eyes. Fear of the unknown is getting the better of you right now. Many before you, and many after you, will find a way to support themeselves and their children. It may not include lots of new video games or toys on a regular basis, but it will be a more pleasant home-life.
As usual... {{HUGS}} and keep us posted.