I'm going to have to go against the grain a little bit here. Unlike most of sexist gaf, I don't think a husband owns his wife, so she's free to do what she wants. And that doesn't make her a "whore" either. There a lots of reasons people cheat, most of them bad, but some are logical. I also don't give a shit about the institution of marriage. It's an ancient tradition based on property ownership and it seems to be forced on most people through society. In my opinion, monogamy isn't for everyone, which is why situations like this arise in the first place. The things you have to consider are; the state of the relationship, your connection with the husband (if any), your feelings for the woman, and whether or not there are children (if there are, I'd encourage you not to do it). No matter what, you're not going to find the answer on gaf. You have to consider that most of the people in this thread are either:
1) Men who've been cheated on.
2) Virgins.
or
3) Wanna-be tough guys.
It's not exactly an impartial group of people. The first two are offended by the impropriety (perhaps rightly so), and the third is looking for justification for their violent urges.
And for the record, the odds that you're going to get killed are pretty low. I imagine you know whether the husband is capable of that kind of thing or not, but I don't think very many people are.
My final thought on this is that if you're in love with this woman, go for it (especially if you don't think the husband is). If not, don't. I personally couldn't bring myself to do it; I saw a cuckhold ball his eyes out on Maury once and it put things into perspective for me. I wouldn't want to risk inflicting that kind of pain, but I can understand why some people would take that risk. I guess I'm giving you a mixed message, but that's because it's not as simple as gaf is trying to make it out to be. Some of the people in this thread sound like they're still living in the dark ages, preventing ignorant harlots from betraying their masters and giving into their sinful, lustful natures.