I believe it is normal to discuss past dating experiences with current partners however I think it is important to be a vague. Current partners do not need to be privy to every part of a past relationship, as each relationship has unique dynamics. I think it is best to be open, but somewhat vague at the same time.
I believe that you should not tell your spouse about your ex. It can only bring up hard feelings or make the spouse feel very insecure. What happened in the past is over and not important. Spouses need to focus on meeting the needs of their current loved ones, and let bygones be bygones.