Guilt over my sister/Did I abuse?/Do I tell my fiancé?

When I was 12-13 and my sister was 8-9 we were playing around. General horseplay and tickling. I remember having this weird/interested feeling to kiss and lick her stomach like I had seen in movies. But right when I did it I realized whoa this is really weird and we went about our day. I literally didn't think twice about it. Neither of us took our clothes off for the record and I didn't reach for her chest area or genitalia.

Fast forward to now, almost 20 years later, I have started to believe that I molested my sister, even if it was purely innocent. My reasoning is that I have a tendency to blame myself for everything and take on lots of guilt. My sister has had a really difficult time the last few years, especially in dealing with day to day stress, maintaining relationships, etc. My knowledge of abuse and working with victims of abuse really reminds me of how my sister is today.

I have become convinced that that moment 20 years ago is the cause of this. I have talked to her about our relationship growing up and she has said it was a perfectly normal older brother younger sister relationship. I have even brought up whether or not she thinks i ever abused her and she said no. She told me that a lot of her problems stem from her relationship with my dad. He was pretty emotional himself and took out a lot of his ptsd on us, but especially her.

I keep telling myself that it was 20 years ago and that it was an innocent weird moment that we all have growing up. But my problems with guilt and blaming myself have compounded this into a real issue for me.

I am about to be married in a few weeks and have become an emotional wreck. Do I tell my fiancé about this and risk losing the love of my life? Am I guilt of molesting my sister?

Thank you for any help you may give.

You are absolutely not guilty of molesting your sister and you should please listen to her when she tells you this. It sounds like you are taking your work home with you and possibly are suffering from some obsessive-compulsive thinking. Licking your sister's stomach as a kid is just daft messing around. It's not abuse. Again, please listen to her - if you see her as the victim (which I truly do not believe she is) then you must listen to her narrative. Perhaps you two need to talk about your dad more together?