I think they would each bug me for different reasons.
Scenario 1: My husband is bisexual. Then it’s straight across the board cheating, in my opinion. I would not think it was sexy or ask to join in if I found him with another man. As a bisexual woman, I wouldn’t allow myself to have a sexual relationship with another woman just because the parts were different. I’m pretty sure I would react the same as if I found him in bed with a woman.
Scenario 2: My husband is actually gay and has just been hiding that fact from himself and/or the public. I would be an entirely different kind of angry and very hurt that he felt like he had to hide from me, of all people.
Scenario 3: My husband is straight and cheating on me with a woman. Well, I would be angry that he was cheating, simple as that.
Scenario 4: My husband is questioning his sexuality and felt the need to “experiment” with a man to see what he really likes. Again, I would feel angry that he had hidden this part of himself from me. However, I would be even more angry that he felt that he could still “experiment” even when in a committed, monogamous relationship. As far as I am concerned, you keep those feelings in check or explore them in ways that are not cheating such as looking at different porn, talking to people about it, going to strip clubs, etc.