I have a friend, Andrew, who I've been amazing with for about 7 years. He and I had a pretty good friend in Ellie, his former girlfriend, and eventually we stopped talking because they had a nasty breakup and she decided it would be best not to talk to me because I'm his best friend and that would be fucked. 

Later on down the road, about two years later (this all happened yesterday), we ran into her while getting pizza for a party. What I expected to be a situation where I had to do damage control for my bro turned into everyone reconciling and making amends, with EVERYONE involved apologizing and wanting to make nice. In short, Andrew, his ex, and I are now talking again and shit feels pretty cash.

In comes the problem: the night that we ran into Ellie, we go back to the party and explain what had happened to the two friends we had there who knew Ellie and all the drama that occurred between her and my best friend. One of them, Sam, doesn't like that she is making nice with him and recommends that he leave her alone cause she is basically a snake in the grass waiting to strike. I talk to my best friend about it and tell him he ought to do whatever he wants, but from the fact that she looked really uncomfortable talking to us (their breakup was pretty bad, with their last interaction being one where he told her to quit talking shit about him) at the pizza place and took the time to talk to us and even gave us a hug showed that she cared bout us still and with that knowledge, putting a good end to that relationship, at the very least, wasnt a bad idea. We agree to talk, with differing goals: Andrew to get a feel for what he wants and I to start being friends with her as soon as possible.

So I'm texting Ellie at the party after dropping off Andrew, and Sam hears that I'm texting Ellie at that moment. She makes a passive aggressive remark about how I am being kind of a creep talking to my friends ex and I get incredibly livid and leave after we're done hanging out. I shot her a text asking to talk and told her the next morning that I didnt appreciate her calling me creepy and questioning my intent with my best friend of 7 years and she responded as follows:

"No it's fine, I didnt think you were being creepy, It just didnt seem very cool, like a violation of bro code or something. Obviously you can do whatever you want, but I'm completely against it cuz ik Andrew was really sad about how things happened with her so I feel it would be best to completely leave it all in the past rather than trying to patch it up, and the knowledge of you being buddy buddy with her might actually upset him when he wasn't expecting it to. Idk, it's just how I see it. I don't want Andrew to get hurt. It still hurts me whenever I hear that one of you guys is hanging out with Jacob because theres still a part of me that misses him and is jealous that they get to hang out with him and I dont. And I think that Jean being polite to Andrew wasn't cool at all, it's just stringing him along and giving him hope when she isnt planning on giving him any. Alex did the same
 to me, and it just made it so much more worse. Obviously she's probably different than alex and being nice because she thought it was best, but with an ex it's just best to leave it alone and let it stay in the past"
(Context: Jacob is a boyfriend that she had for a few years and broke up with, and Alex is a boyfriend she recently had who she knew for a couple months, of which she dated him for one of those months, and he broke things off. It really crippled her emotionally)

This further frustrates me as it implies I'm putting my best friend in harm's way because I want to be buddy buddy with someone behind his back (he knows and approves of us talking) and he had stated several times he doesnt plan on dating her in any scenario. I talk to Andrew about what to tell her, and after a bit of deliberation, tell her the following:

"He had said a few times that he just wants to squash the beef there, he isnt interested in pursuing anything. And I wouldnt Express interest in someone who is going to fuck with my friends (let alone Andrew), and i wouldnt advise him into a shitty situation.

I do appreciate your concern for him, however. While we both have differing views on what's best for him, I do value that you are bold enough to express what you think is best and care enough to give thought and input into the matter. Again, I dont agree with your take on it, but I do like that with important things in his life you dont just go 'eh, whatever' about and ignore it."
(Context: the last bit was me trying to put a good spin on the situation, as I felt I was being a bit rough about what I was saying, and I've been trying to make her feel more at home in our squad, so I wanted to make it clear that her care, as wrong as I think it is, is appreciated because care is care)

So that leaves me at this: I've been overthinking this whole thing and I feel like I might have been a dickhead SOMEWHERE in all of this. Maybe I'm fucking up in advising him to talk to her, maybe I fucked up in how I talked to Sam, idk. I just feel I fucked up somewhere and want to know where so I can correct it.

AITA in any of this?