I have been in a very similar situation. I met a guy, fell in love, he was married (no kids though). He had been married for 18 months, said he didn't love his wife in "that" way and that they were more like brother and sister. I left my ex and moved into own flat. His wife found out, kicked him out, he moved into own house. I thought happily ever after was just around the corner.
We had a year of trauma - we're together, then we're not together, he feels too guilty, she needs him, then we're back together, then they go on holiday to try to sort things out, he comes back and immediately contacts me, etc etc. It was hell. My life revolved around this dreadful relationship which caused me endless stress and ended up with him on antidepressants.
But... we have now been together for 10 years, married for seven years and have two wonderful DCs. He is my best friend and a wonderful husband.
I guess what I'm trying to say is just pull back, get on with life and wait. I know its hard but at the moment he is torn emotionally, feels guilty and is under tremendous stress. It might not work out. He might get back with his wife and you might not hear from him again. But if its really meant to be he will come back to you. Get on with your life and things will work out for the best one way or another.