Example:
Your friend's girlfriend is pregnant and he comes to you saying he's going to drive her to the slaughterhouse. You say OK, see ya later. You have acted as if abortion is OK when it is evil. You have therefore sinned by consent.
Now take Forlorn's advice. Stop mulling over sin. Find something else to occupy your mind.
I second this advice.
You need to spend more time in spiritual direction (make sure to TRUST and OBEY your confessor -- that's the antidote to scruples.)
Remember, the devil can get you with scruples as well as with temptations of the flesh or other classic sins.
The devil plays the "long game". He'll tempt you to FAST, then tempt you to over-do it, and eventually you flip 180 and end up a glutton.
devil 1, You 0
The only solution is humility and obedience to your confessor. Get a regular confessor and make use of confession to expose these temptations of the devil. The devil hates his temptations getting an airing in the light of day.