How do you want yr "You've been cheated on?"

The eps of That '70s Show where Kelso is an idiot and loses Jackie made me wonder,

What is the "best" way to find out your bf/gf is cheating:
a) Catching them -- so there's no confusion about what the truth is.
b) Hearing about it from a friend -- so that cheating scum doesn't get to see you cry.
c) A confession from your bf/gf -- so you don't have that image burned on your eyeballs, and they're kind of showing remorse? A little? And maybe you could forgive them?
d) Other... please describe.