I took a few days off from reading, and I've come back to this, you finding out that your H has been up to his nuts in fluff while prentending to be the perfect father. I can't say that I'm surprised as it was my feeling for a while that there was someone else, but I'm sat here feeling a combination of sadness and anger.
Sadness cos I wasn't there for you and I know how you are feeling now, and anger cos I just want to knock his block off cos I feel your H is being a total ****er. Ok got that off my chest.
I haven't got any specific advice for you, but my general advice would be to look to our good friend John(210) and see how he pick himself up and moved his life on after being in a similar postion.
There is life after being hit by the cluster bomb and I'm sure you will be strong enough to map a way forward.