Why is my husband FB friends with his ex fiancee?

Dated for 10 years, bought a house, engaged on our tenth year anniversary, married for almost 7 months

Yet...he continues to be FB friends with his ex fiancee from Florida. He was engaged before we began dating , but never spoke about her, until my mother in law said something.

He doesn't use his FB at all, but bothers me that he has her on his FB list.

She's married, not going to lie, but I've snooped on her FB and linkedin, and she's a PhD doctor, and married, so I'm a little bit intimated by her

But why does he still have her on Facebook?!

I've asked him about it awhile back ago, but he has denied to ever talk to her

I wish I can just go to his FB account and block her myself. Because she sees everything I post on his page and makes me feel uncomfortable.

Can I block her from my FB that way she can't see anything I post on his Facebook?!

Suggestions please

Thanks!!

Ohhhh.. and she also has colored eyes!..that bitch...