My head is spinning just reading your posts. So many great people posting to you including Mr. Bond and you ignore everything. We have all been where you have been. We have all done foolish things but most of us make the mistake once and move on. You keep making the same mistakes again and again. You are only making yourself feel worse. You say your sons grades are slipping this is NOT just because your h left. You can fix this.
My h left when my youngest of 2 was one year old. He had multiple ows. I am a full time student and my children are straight A students. My oldest is a talented singer and my youngest is an excellent athlete. This is not because I sat around feeling sorry for myself. When I had a bad day and there were many I did not show them. I found other coping mechanisms including posting here.