I am so sorry.
I have a very good idea of your pain....and just the glimmer is awful.
Please get support....Al Anon/Families Anonymous, etc.
It is hard, but do whatever you can to not let this infiltrate other areas of your life. What good will it do? Nothing.
You've done you best. I'm sure as you are able, you will try to help. But you can't let helping him, hurt you. You are worth more than that.
Cry as you need to, tap into your spiritual beliefs...get support....put one foot in front of the other and inch forward as best as you are able.