I lie to my friends that i am 16.

Yup. In reality i am 13. The friends in question are 20 and 18. They are dating. I made friends with them on reddit a year ago where i told them that i was 14. In reality, i was 11. I met them a few days before my birthday. I turned “15” where I actually turned 12. I turned “16” now where I actually turned 13. i am extremely close to both of them in fact i voice call the 20 year old almost everyday. i feel like if i actually tell her the truth that she will no longer be comfortable with me as we have a 7 year age gap even though im her closest friend other then her girlfriend. Shes the closest friend ive ever had so i dont want to tell her that im the age i am just incase she thinks its weird and leaves me. Its came to the point where im about to meet her irl. She wants me to be the best man of her and her girlfriends wedding. I can do both without getting caught but i really dont know if i should tell her or not.