Ideally, in marriage, husband and wife are able to talk directly to each other about what bothers them. But we need others to talk to also, bounce ideas & and feelings off of, or just vent so we don't hurt the person we are venting about.

Sounds like your husband was venting to his friend, and maybe seeking some advice or simply needed to talk to someone other than you about his negative feelings about you.

The only thing I find odd is the friend's reaction. For him to not understand the relationship dynamics above and feel he has to act ashamed that your husband is his friend and confided in him, or worse, that he has to take sides and treat you bad, is childish and unhealthy.

Maybe you should talk to your husband about THAT. Let him know it's okay to have a friend to talk to, vent, what ever, but maybe he should let the friend know that he loves you and the friend shouldn't treat you any differently just because your husband is blowing off steam or using him as a sounding board.

Or you could try approaching the friend yourself and explain this, if your husband isn't capable of it.