I'm sorry to read of your situation. What prompted him to tell you now? Most cheating spouses don't fess up to affairs unless they are caught with a smoking gun. What makes you feel this isn't the only time?

Wishing you well.

9 years ago his friend went missing, it's prompted a local search for him .... we did find him he had died sadly, I received a phone call from a women enquiring about my husband and his friends death, my husband and his friend worked away together 12 years ago his friend died 9 years ago, apparently his friend had an affair with this womans sister...... my head went into over drive but he denied any affair himself... back to your question one of his friends now has had an affair and split up from his partner.... I told him what I thought of his friend and I have always asked him about my doubts about him over the last 12 years, then bam he confessed, I feel sick with the 12 years of lies and I feel sick about his affair that ran along side his friends who died....I feel in my heart my marriage is finished even if I can try to go forward in some sort of relationship with him.....I have taken my wedding rings off I will never put them on again. .... I do feel there is more to come because I could not press him at the time due to his grief and his sadness , he lost all control and became unbearable at that time..

My heart just sinks at what you are going through. And based on what I have read from you, I personally agree that there may indeed be more to come. Some people do indeed only fess up when confronted with "smoking guns". But I also know that a good number of people have enough conscience that they could not live with the knowledge of having done what they did - eventually they just can't take it anymore.
Having said that, one of the rules of "affair discovery" is to not make major decisions quickly when the emotions are so raw. The easy thing to do right now is to ditch him - and the marriage. And no doubt - the marriage you thought you had is indeed over. But that doesn't mean a new one cannot begin. Admittedly, you must be committed to going through what will be a long process. And the things he absolutely has to do to keep this marriage going must far exceed yours, beginning with FULL disclosure, the ceasing of all contact both with the person(s) he had the affair with, and evidence of his sorrow and willingness to do whatever has to be done to build a new marriage.
I can't speak for you or him or your marriage. But what I have seen through the years is indeed impressive in terms of building a new marriage. I will pray for that - and for both of you.

He has done such a good job of lying for 12 years that I can't trust what he says... my emotions are in turmoil, I have had one hell of a month, I have now lost my job (my brother was my boss) over a disagreement on pricing but on a positive note the mammogram I had last week came back good. ... just need some normality

Im sorry it happened to you.. but im a little bit confused here.. what do you mean there is more to come? and what grief and sadness are we talking about here? Is it the gried and sadness because you took off the ring?

Maybe the guilt was eating him alive for 12 years and he finally had the opportunity to come clean.
Don't mean he's been cheating for 12 years.