I am quite certain that no one feels that they wasted time. Everyone here hates to see you suffer. Sometimes we give something the best that we can and that is all we have to give. Nobody will understand the trauma of having this happen a third time while you were pregnant, caring for young children and working/going to school. I know I don't.
I'm amazed that you have carried on with your school and work and taken care of your boys. That is commendable. From everything you've said about this guy, I can't help but believe that you deserve far better than this. I know that it doesn't help to hear that now, but with some distance you will know it for yourself.