I'm an amateur adult film actress for 2yrs and I haven't told anyone I know including my boyfriend of 5 yrs
How does one become an amateur adult film actress?
You just have to contact the right people.
You have to tell him something like this. After five years, it will be difficult, but if you have a solid relationship, hopefully he'll understand why you felt so uncomfortable sharing it with him.
He loves me.  I'm afraid this'll break his heart.
If he loves you, he'll be able to look past this.  The longer you hide things from people, the worse it gets when you finally have to tell them.  Get it over with!