Friends fallout (I'm not involved) affecting my friendships

So about 6 months ago, two of my school friends fell out with each other (they were also friends). I was never involved but each of my friends told me about it separately (from their sides). From then on one of those friends keeps asking me if the other one has said anything. The other one told me she doesn't want to speak to her again, and she refuses to talk to her. However my other friend is very upset.

I don't want to take sides and haven't, and their stories are both different perspectives. I don't know who to believe but that's not the issue as I don't have to believe either of them , I'm not involved.

I have been struggling with my MH a lot recently and so I have been quite isolated from friends. My friends issues with each other has been too much additional stress. So I haven't really spoke to my friends much.

I am very upset as I reached out to one of my friends again, trying to meet up over Christmas and everytime (literally) I meet her she says she is very sad and asks me every single time I see her. It upsets me as it feels like it's affecting our friendship. It also feels like that's all our friendships based on -her trying to get back her friendship with my other friend. I try to listen to her and say sorry to hear etc. but I do say I'm not wanting to get involved. It's not just I don't want to get involved , I actually can't remember the story correctly myself so I worry I'd say something wrong, I don't want to take sides and want to be neutral. I wasn't at the incident where they fell out, so I only hear stories from each side.

I haven't actually spoke to my other friend in a while but she no longer brings it up. It's stressing me out, and I'm feeling distant with my MH issues alone and their fallout just makes me want to isolate myself from them more etc. I am trying to improve my MH and get more connected with friends, but I text one friend asking how she is, and we should meet up. I got it late and by then she'd already sent a text asking about the other friend (if she had said anything to me regarding the incident, and that she is ignoring her messages etc.) before I could even reply to the general chat text. I wasn't even at the incident where they fell out.the other friend and I don't even talk about it at all.

Then when we meet up , I say I'm not involved and sorry it's upsetting you etc (I try to be sympathetic) yet at the same time I know my other friend doesn't want to talk to her etc. But that friend as soon as I say it she keeps asking me over and over again.

Please I don't know what to do, it's upsetting me, stressing me, making me want to distance myself more, an extra stress on my already challenging MH issues. And I feel sad as it feels like all my friendship is based on with one of them, is trying to become friends again with the other friend.