No, hell no. You should not have to think about this at all!
In the civilian world, doing something like this at the VERY worst might get you killed (if the Marine husband is a psycho), but more than likely would only result in a fist fight if that. It wouldn't necessarily result in any sort of legal action against you.
However, in the military world, the consequences can be a whole lot more severe in terms of legality...stuff that CAN follow you to other things.
An interesting article, written by a former 'first shirt':
http://usmilitary.about.com/od/justicelawlegislation/a/adultery.htm
The gist is that although there is NOT a specific offense against adultery in the UCMJ, commanders and legal offices have a LOT of leeway in prosecution.
Oh, and one more thing...if you two decide to do something, and later on, her husband finds out and she claims 'rape', you're done. Even assuming they find out that it was all consensual and she was lying, the amount of grief you will have to deal with will exceed anything you have had to deal with before...especially if it comes down to 'he said, she said'.
No piece of ass is worth a career...no matter how hot she is.
FC