Guilt and regret

Hello Mam/Sir 

I am having this problem or urge that i need to confess or tell someone what i did back then but i am afraid of the outcome of my confession. My mistake in the past is that when i was 12 yrs old i think. I am 18 yrs old now btw. Me and my cousin did some sexual play such as blowjob and handjob. It is because of my curiousity as a child to sexual acts that i why did it. I am the one who convince my cousin to do it to me back then. It is only now that i realized that i did such a terrible mistake. I am feeling extremely guilty for what i did. I am afraid that he still remember those memories and will not forget them. I am afraid to tell it to my parents because i know that it is shameful. Do i have really have to confess and tell about it? when i did it because of my immaturity and i did not know better.