Before jumping into any conclusion, think 1000 times. May be there is nothing, may be it's just a misunderstanding. Who knows he might not be cheating on you. If he confesses that he is cheating on you then move on, do divorce in mutual understanding. Talk to him properly, understand his problems first. And let him understand your problems. Think big.

It's sad to know that he is cheating on you. Ask yourself first if you have ever cheated on him or not.