There's nothing saying you can't send an email to each of them, saying basically, "just wanted you to know I appreciate all you did, even if it might not have s

There's nothing saying you can't send an email to each of them, saying basically, "just wanted you to know I appreciate all you did, even if it might not have seemed that way at the time." If you stay in touch, they'll see that you've put lots of effort into fixing weaknesses. After all, the person you least want to go into business with is one who can't recognize and correct their own mistakes. I've stayed in touch with a co-founder from a previous failed venture, and while it hasn't come up to work together again, the contact has been very valuable both ways. Lots of bridges can be rebuild, assuming you have the desire and humility. And don't think they don't regret some of the things they did. There's always plenty of blame to go all around.