I KNOW we need a LOT more info.

Ex pissed off boyfriend towards op. Ex pre apologized for the rant. Maybe it was or was not intentional to get between them. Some stay friends with exes. But yeah, lots of missing info.

His ex is also the mother of his child. She has been wanting to go off on him for various reasons, which I told her was a bad idea, trying to keep the cool amongst all of us. But, my boyfriend told her he wanted the iPhone he bought for her a few years ago back, and she decided to tell him that I have been telling her various things about our personal life. This was not true, and she only said it to make him mad because he wanted his phone back. she messaged me on Facebook Messenger saying "I'm sorry" before he blew up on me over text. we got it all figured out, everything is fine now, but I like her a lot less now for lying about things just to make her ex (my boyfriend) mad. She was only being petty.

Um, tbh your BF sounds kind of petty as well for wanting a phone back that he bought (presumably a gift) a few years ago. If he'd bought it and they'd broken up very shortly after maybe? But you lose all right to ask for it years later, imo.

Frankly your boyfriend doesn't sound great either if he chose to blow up on you (by texts no less, how immature) before he even heard your side of the story.

Good to know that I’m not the only confused one

what guilt? there's no info about what actually happened. his ex could have just as easily accidentally spilled a secret.

Can't you read between the lines? Clearly, the boyfriend slept with the ex, she felt bad and apologized. Instead of defending himself against the OP's righteous indignation, he went on the offensive to cover up his crime.

First, not her number. She specified Facebook Messenger. But not odd if bf and ex have a child together. No doubt the boyfriend gets visitation with the child and the op is around for some of that, so there would be a reason for them to be able to reach each other. I know if it were me and my ex went off with our child and a bf, I'd want to be able to contact him.

Could be in the same social circle.

Yes, that’s obviously what that means