She's trying to break us up

I was going through my boyfriend's phone and I found messages between him and this girl he's friends with talking about our relationship. He was asking her if she liked me and she told him (I'm paraphrasing) " I honestly don't think you should have gotten in a relationship. You have shit you need to work on mentally and if it doesn't work out you're gonna break apart and be back at square one. I don't think you're mentally ready for a relationship ". It was a bit longer but that's me paraphrasing. I askes my boyfriend about it and ge tried to shrug it off and told me not to worry about it. I told him I don't want hjm talking to someone trying to break us up. He snatched his phone back and we argued about it most of the night until he got his stuff and went home. Am I wrong to be upset over this?!