If i were dating for six long years, and then my partner cheated after our marriage, i wouldn't trust him to have not been cheating for earlier long dating period. In other words, i would have to question whether there was any real monogamy throughout the relationship and the trust issues would always weigh heavily upon the relationship.
Material assets can be a big draw to stay, but the fact is that you can replace items, just as you can replace a relationship that doesn't hit the mark.
If it were me, i would find my own composer without a man, but i don't think i would walk away from a possible relationship with a man that provided me with emotional security. I suggest that you find your own way to personal security, by further education if necessary and finding your own job security. I would date the other man, while working towards your own personal security.
Here's the deal. Relationships that start via adultery most always fail. Because it starts under a cloud. And there are trust issues because it started with the knowledge that the person has the capacity to cheat.
So, if you want to be with someone else, end your relationship fully before starting a new one.
But, I'll say this. You'd be wise to NOT be with anyone right off the bat. You're hurting. You're in a bad marriage. Often, without realizing we're doing it--- we grab another guy that is familiar to us in some way and get those woozy feelings for them like a band aid. There is no foundation there. Rebound is real. And it often ends in our not making the best choices for ourselves. So, you should take a break if you divorce to be YOU> No men involved. Get strong again and then pick the best person to be with at that point.
good luck
If there are no kids, and he cheated on you more than once, and you don't love him that much (frankly it's not hard to understand why), it's probably time to go. Material possessions or concern for your position as his wife are no reason to stay married, you should stay married for love and leave if it has worn out its welcome, unless you have children counting on you to stay.
It does seem a shame to run immediately into the arms of someone else without having a time where it's just you, figuring out who you are without a man as a shield, though. See if you can do that.