Wow, that's something that I would love to....you know, to slp
with an ex. Well, actually I had such experience too. But not drunk
kind. We broke off and still miss each others. After that, I felt
the same as you too!
My advise is to stop doing that. Remind yourself that you are not
her b/f anymore and it's not right that this is happening. If you
really still love her, then let her know that you should not be
doing this as a "Friend".
In case, next time both of you get back again. This thing will not
be a "Dark Side".
Worst....If somehow things turn ugly between the two of you in
future and maybe, (I say maybe as I really dun know how she is as a
person!) what you did with her became a "weapon" against you.
Nobody has the right to say what you did was right or wrong. What
you really want determines your actions. And your actions will have
consequences. So think properly. Wish you luck!