Go In Swinging and the second option for Crime and Punishment say they get a bonus to attack, but your characters cant attack this turn. So...what happens? Does it cancel my attack?

Nope it just means after that attack you can't attack anymore.

once you've exhausted to attack, nothing can prevent your attack from going through except if the attacker or defender is removed from the attack. so in this case, the attack still goes through.

They are all right.

So, if the card did not mention when it is used, used it for your last attack. The attack that you last wishes to propose.