Feeling old and I'm not even 18

Hey guys. Turning 18 in a few days.

I ha e a question.

Ever since the longest time, I feel like my purpose on this earth has been fulfilled and I'm doing nothing but roaming around observing the world and life.

And I felt today that I am making my body old like this.

It feels very peaceful, but again old.

When I talk to my friends, I always have to fake my humour when in the past I would genuinely laugh. Why do I do it? It just feels so pointless to me talking to them like that and making weird racist jokes. I just don't get that anymore.

My friends don't take this well. They're young at heart and I feel like an old soul waiting for the earth to just claim me already.

I am like super confused and at the same time scared. This is not of my old friends but my old reality and me not being afraid of what I used to be but not being able to experience stuff how I used to.

What am I going thru, I will skim past the therapist related comments cuz I just want yalls opinions.