Just found out that my husband of 20 years has been having a relationship for the last two months, he says he was going to stay with me until our youngest child went off to university in two years, but now that I've found out his plans have changed, my son is due to do his GCSEs in three months, we can't do this to him now, so we are going to have to try and carry on as normal until then. My whole world has been blown apart and I'm struggling to know what to do.