Am i being a bitch or should i really tell my best friend about the red flag & warn her?

have to post this somewhere where people might not judge me but i might be judged. It’s okay. I know i sound bitter & hateful but I’ve been through so much crap that i don’t know how else to put this

So I’ve struggled through two relationships & my best friend has seen it.

I think she has a new boo & she’s never had a boyfriend before (were 25)

And i get that she’s like feeling all good or whatever but she told me something two weeks ago that was like a red flag. Idk if she knew it was but she still stuck up for him

She said she caught him looking at another girls Instagram and then lying about who it was.

When we were talking about how my ex would shut down & run away sometimes she was like “oh yeah (insert name) doesn’t do that he ALWAYS tells me how he feels”

I’ve seen enough crap & I’m not as naive as her. I don’t wanna make her unhappy & i don’t want her to think I’m being jealous because i am slightly jealous because she’s been annoyingly happy & she thinks i don’t know why but i do know why. I miss being that happy over a guy, over someone new.

But something tells me that this isn’t gonna go well, she’s too trusting and way too nice. Idk if I’m being jealous or if i should tell her? I think maybe i should just keep my mouth shut , i don’t want her to think I’m a bitch.