bones you can file for adultery if you have absolute proof of cheating, otherwise you can go for unreasonable behaviour if you don't want to wait the 2 years. I went for UB on the grounds that he was communicating with another woman and had left the family home and moved in with her and her husband.
Your H has created a sorry mess if it is a colleague's wife and yes could have implications for his work. I mentioned earlier about telling her H, and that I left it too late, but I myself did as others here have advised and waited until the finances etc were sewn up, as it is easier.
With this new information, you really do need to push ahead and get everything sorted out. I know it is hard, but if he loses his job at some point, he will come after equity in the house, even though now he is saying you can have it.
See that solicitor and get the paperwork drawn up and signed, and start the divorce off. Your solicitor will of course advise you on what to do.
Just keep on, one day at a time. I survived on a banana and half a sandwich a day, plus lots of water and a multi vitamin. I felt as long as I was having water and vitamins, I would survive
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I don't know if you looked at the leaver and the left, but I have put a link here as it describes it very well, and was given to me by my counsellor.
theparentconnection.org.uk/articles/the-leaver-and-the-left