The ex sounds a little dangerous... I think your bf should help set the friends-in-question straight. He needs to have your back... If these "friends" dont really matter, I wouldn't worry about it so much. But you and bf are going to continue to be around and do stuff with them, I'd make sure they were informed properly.

How does bf feel about the situation??

The ex gf sounds manipulative. If those people who don't talk to you anymore were really your bf's friends, they wouldn't want him to be with the ex. It sounds like the two of you should make new friends together.

I tell you something - if you want your bf - and no arguments (not as much) make your world small if you want to hold onto him .
Stay away from groups .( where 2 or more is gathered evil occurs) . And don't not expect it to happen cause it will cause if do except it , you'll save yourself a lot of pain , causecif you don't exoect it , the shock if he does anything wrong will cause you a lot of pain and trauma .
I ended up in a pysche wards for 6 weeks over my ex cheating on me with this fella cause his friends said me that i wasn't socializing cause i used to be fine and happy when she used to go out in the town on her own , and one of his friends switched it around to make me hang around with them and said i was very insecure and that i wasn't enjoying my life when she used to go out .
I ended up in a pysche ward over one of the madest break ups in a relationship history .
That relationship entered a load of lunatics into my life , pysche wards for 6 weeks .
So my advice - make your relationship small , as in entering other people into it .
YOU SAVE YOURSELF A LOT OF PAIN .
And say yo your bf that you want his ex out of his life .
Thats the kinda shit that could lead to a pysche ward . Thats what i mean

I still talk to some of my friends I made when my ex and I were together, but I have no idea how they feel about her current boyfriend (I don't ask). I will say this: be careful.
On one hand, she could very much want to get back together. On the other, she might very much want just to be friends since they were together for so long. The circle may sense your unease and interpret that as jealousy, and when that happens they will certainly ostricize you.
Don't do or say anything bad about her. If she comes up, try and change the subject. Keep your focus on your boyfriend, and if they only focus on her then just brush it off. Hell, even say nice things about her so that no one interprets you as the enemy.

I’m not sure there’s much you can do other than keep good communication with your boyfriend about your feelings. He doesn’t sound like he’s friends with his ex still and he can’t control who his friends affiliate with. All you can do is keep being a positive presence in his life. If she’s a lousy person then eventually it’ll become apparent and she’s scurry back under the rock she came from.

Its weird how in life many many people are all someone elses "ex".
Yet its hard to forget the previous person,and we go through life trying to replace the previous person.So we meet person number 3,hoping they will be like person number 2.Who we hoped would be like person number 1.
I think people are very lucky if they meet one person they feel settled and happy with-of course thats a two way street isnt it?I wonder why our relationships are so hard?

If you do socialise with those friends of his at anytime in future, bring the issue out in the open with your bf present. Tell them the truth about your experiences of this woman, the history of the relationships, and the fact that you too are good together and thinking of marrying.
Honesty can resolve most situations.

It's her or you. You don't become friends with your Ex. Everything about her she needs removal and blocked from social media. 8 years is half of your youth. My significant other and I have been together for 8 years. So the wound is still fresh. But he should be less forgiving and Move on

She wants him because he's with you. If you dumped him she would immediately lose interest.

Sounds like you have a dud on your hands. After three years if you are not already married you never will be. He isn't interested in marriage.

Good luck why waiting plan that wedding and start the family life dating is for people not sure about their partner.

I think it is time for the two of you to make new friends.