I posed the question about talking to him for a reason.
It seems you listen to what people suggest.
That can be taken two ways.
In any event. The day you found cum on your bed and caught your son, there, and your top un-done and your breast exposed is the day you "should" have discussed councelling.. He is not 14, 16, 18, 19.. He is 24.
If this is real, why did you wait for more to happen? And, why did you feel the desire, to do as you did to your husband?
I appreciate you are a victim but he has always stated " But Mum I have fantasized and you have stated, he almost did it, or he did something and I knew, before".
Where does that blame therefore lie in totality?
If this is real, you need to also tell your Son you knew what happened before, take the responsibility of for what ever reason, being excited at the anticipation that you expected and keep it going for hours, yourself, like I said, after the alcohol would have started to warn off.
And if not? Then understand, people are there for you and then, they are not fools either..
What ever is the reality, don't be shy to write back... Things do happen like this, that is reality.