I have been cheated on but I haven't lost anyone I was dating. My response.
It's worse for your spouse to die, than to have a spouse cheat on you and leave you because it's a lot easier to come to terms with someone cheating on you and leaving than it is to come to terms with the person you love dying and being gone forever. When someone cheats on you and leaves you go through a lot, but at the end of the day, you pick yourself up, dust yourself off, and move on. You'll be able to go long spans of not even thinking about it until someone brings it up say, in a forum thread...
But having a spouse die is something that will shake you forever. You'll try to move on, but that knowledge that the love of your life is gone will always be a part of you. Every morning for a long time, much longer than you wake up missing your ex, you'll wake up not remembering she's gone at first and then realizing that she's gone.
Having an ex that cheated and left you may change the way you think about women, but having a spouse die will change who you are, maybe forever.