Is it normal to do anything with your cousin.i was 13.

I want to explain a story which happened to me at the age of 13. On my 13th birthday, We sat with the family to eat ice cream cake and blow out the candles. After that my (girl cousin) takes me upstairs saying I have something to show you. So we went upstairs not knowing what the surprise is. When we got up stairs she locked the door from behind and started to undress herself. My eyes lighted up because I actually saw some breasts for the first time of my life and I was excited. I started to suck them and she got real into it.She took my pants off and started to suck my penis. I am a shamed of saying this but that was my first time then and it felt so good at the moment. This started to continue for like 4 or 5 years but we never had fully sex just oral. When I was bout 15 my grandmother caught us kissing together and told us to stop. The funny thing is I had no feelings for her. At the age of 17 I came to my senses and stopped because I realized we were actually blood cousins and it makes me sick to say it but yeah we were. To this day we still see each other. We smoke weed, drink, but never bring none of it up at all or even discussed anything. I really regret what had happened and I think she stole part of my life away.