It is very good you found out the truth sooner rather than later.
It is almost always better for a person in a marriage to "settle that situation" first. I.e. don't assume the person you go jumping to will absolutely be your safety net. Make sure - even if you ended up alone - that you would be content with the choice to divorce. Make sure you have a real safety net in place (not just relying on the "other man"). That way you are not setting yourself up for disaster.
