I am back after long time and I see floods of questions related to incest in this site. Not sure if all them are questions from real world or just time pass questions, I feel the latter though. However, by going the way usually followed by fellow member, I give benefit of doubt and consider it as real world question.
As I always mention, sex is result of both bodily and psychological desires. And same is outcome - body and psychological. My answer also lies there. While your body will get what it wants (orgasm) by having sex with anyone you like, be it a brother or a beast. But mind is a different game.
Body forgets the pleasure after few moments and wants it again. While mind will get full pleasure .......But after few moments...thought process may change!!! How? All this depends on our cultural background and many many things. If you are really least bothered about culture and moral aspects, your mind will really enjoy bodily relations with anyone including blood relatives.
However, if you have dual personality (respect moral and cultural values) your mind would suffer huge blow after you have first sex with your target and suffering would remain for long time to come. Your mind would think about impact on your brother and your husband *ONLY AFTER* the sexual pleasure is over.
So analyze yourself before you step further, take informed decision.
All the best !!!