Should I stay or should I go?

Serious answers only please. I have been married for 20 years. It has not been easy and I have been unhappy for probably most of those years. One reason is this, my boyfriend before I got married broke up with me pretty harshly with no reason at all. I was expecting a marriage proposal from him. For the past 20 years I have wondered what if. I married my current husband just because I could, it wasn't love, at all. Well, the ex-boyfriend has come back into my life. He gave me a pretty forgivable reason why he broke up with me in the first place. I am still unhappy with my current husband and have wanted to leave for sometime now. The ex is wanting to try again. I want to throw caution to the wind and just go for it. What would you do?