omfg, wall of text and i actually read all of your post, i make
it as simple for you
you are going to get married soon, and i think, in my humble
opinion, if you still want to get married with your current
boyfriend, don't tell him anything, it is for his sake also,
imagine the looks on his face, and how much he will hate you for
the rest of your life, maybe!
i don't know why you actually commit such a mistake, but i do
understand why you do this, at that moment, that manager comfort
you at that moment, when you are at the most weak, and hurt, to be
honest, you don't have to end your life over such a thing, do you
want to get married, and forget about what have happen, or tell
your boyfriend, the thing that happens between you and your
manager, it is crap when someone tells you - i am sure, your
boyfriend will understand, or he will forgive you,
if you tell him, worse comes to worst, the relationship, will ends,
you will end up in greater misery, and this will haunt you forever,
or bear the guilt for a few years, wait till both of you have
settle down, and then tell him the TRUTH.
the truth always hurts, and when it strikes you down, you may
regret the day, that you tell the truth, sometimes, a white lie,
will save you alot of trouble.