Mistakes and which sin?

[gryffg1]

A couple of months ago I have made a terrible mistake that I will never do again, it started with peer pressure from a friend. After I did it I immediately fixed my mistake, but no one knew besides my knew friend. Since those couple of months I have still felt awful about my decision even though I fixed it. I kept researching things up. Even though no one knows about it I still had a massive amount of guilt. I looked up what sin the thing I have done would fall under, and it said that it could fall under mortal sin but for me since I know I will never do it again and that I fixed my mistake and prayed that it would fall into a venial sin. Please give me some advice to help me move past this. Thank you.

 

[Fauken]

Please give me some advice to help me move past this. Thank you.

Have you gone to confession and discussed this with your priest? If not, do so.

 

[Cor_ad_Cor]

Mortal sin vs. venial sin is determined by the circumstances at the time, not what happens afterward or how you feel or what you’ve resolved. Please consult your priest. We can’t really help beyond that.

 

[CRV]

After I did it I immediately fixed my mistake

That part is separate and should follow on as part of our reparation - for example if we say something false about another to our friend “She’s a liar never tells the truth” to our friend, then we are to fix it by telling our friend we lied because that isn’t true and that we shouldn’t have said it.

but no one knew besides my knew friend.

Depending on "what’ it is, e.g. detraction or calumny it limits the damage done, depending again on what was said. You also forget God knows.

I kept researching things up

Please don’t do that. You won’t find the answer you are looking for. You need to discuss this with your priest, preferably in Confession.

it said that it could fall under mortal sin

If it is grave matter, yes. If it isn’t then no, it is venial.
If you knew before you did it that it is seriously wrong - then yes. If you didn’t know, then it becomes venial.
If you did it of your own free choosing, then there was full consent.

For a sin to be mortal - grave matter + full knowledge + full consent is necessary. Any of those three components are not present at the time of acting, the sin is venial.

I will never do it again

= Firm purpose of amendment which is part of the Act of Contrition.

prayed that it would fall into a venial sin.

praying/hoping does not change the fact of the gravity of the sin after committing it.

Please give me some advice to help me move past this.

Go to confession and confess what you did to the priest and be guided by him.