Should I tell my friend others are talking about them????

Context: My lunch table consists of 3 people (just counting the ones important to the story). Grape(16 F), Blackberry (16 F), and Mango (16M). Blackberry and Mango have been friends for as long as I’ve known them and Grape just started sitting with them. Mango sits with us every OTHER day. BlackBerry is still in love with her ex, Lemon(16f), who is friends with both BlackBerry and Mango. BlackBerry and Grape dated in middleschool

Actual Story: Grape started sitting with my table about a month ago and a monthish ago started talking smack about Mango with Blackberry. BlackBerry is upset at Mango because he doesn’t like his ex (Her bsf). Grape just doesn’t like him. After they started talking, BlackBerry started being weird and passive aggressive to Mango, which he noticed, but knowing Blackberry’s in kinda a funky mental state, kept being friendly.

The passive aggressiveness started getting to Mango tho and he decided to ask Lemon if BlackBerry was stable enough to have a conversation with. Lemon said no, but then turned around and told Blackberry that Mango said he felt like she was being mean and that he thought Grape was kinda a bad influence. Blackberry took this as him telling Lemon (who she’s still in love with) that she was talking to her other ex (FROM MIDDLESCHOOL).

As kinda the bridge between Mango and Blackberry/Grape at this point, should I tell Mango that Blackberry (who he’s still being nice to) is talking shit about him and that he prob shouldn’t trust Lemon with stuff about Blackberry, or just leave it?