His Ex

So my boyfriend and his ex are close and I don't care because his ex is really chill with me but she sketches me out. Last time she was over she asked him if she could "experiment" other people like they were still together and I know she still wants to be with him because of what she texts him and everything but I know my boyfriend loves me and wouldn't do anything like that to me. I just don't know what to do about it because I don't know what she's thinking in her mind because they're were together for 8 years and I've only been with him for over 1 year but she broke his heart and told him she didn't love him anymore because he wasn't showing any emotion to her anymore but I understand that, he was gonna propose to her and she broke up with him a week before and she doesn't know so what if she knew she propably would've tried to get back with him. She's his best friend after me, like he always assures me I'm his baby and he loves me and wants to spend the rest of his life with me but I feel like she wants to be with him still, she even told him after they broke up "if I want to ever have kids it's gonna be with you, I don't care if we aren't together" how should I feel about it?