First off, expect the rules to chance. Both of you will find that what you feel is acceptable will slowly grow to encompass more situations and people. When we first went open, we were allowed to do very little by ourselves, a little bit of kissing someone else and that was it. Now we are fully open and can do what we want on our own. That has now given way to broadening our interactions with others.
My partner has a few guys that he's close to, one of them that he spends the night with once or twice a week. I have a guy that I am seeing and it definitely looks like there is a genuine relationship starting.
Make sure you make "Communication is Key" as your new personal motto. Make sure your husband knows without a shadow of a doubt how much you still love him while you are embarking on your new relationship so that he knows that this new man is not a replacement.
A major rule that we have is that we do not start anything with someone new (Sexually or fledgling relationship) that we wouldn't not introduce to each other. For us, transparency and honesty is the key.
My current dream is that my new guy can meet my partner and become genuine friends and trust each other because they both have my best interest in mind and care for me.
DsmEvolution = Male / 33 / Gay Flexible / Open Relationship / With Primary partner for 12 years / Possible relationship starting with someone new. Details to come