Should I be worried?!

So a while back this girl messaged my boyfriend asking if he wanted to go for a blunt ride. I got mad about it cause like why tf is she asking him that?! Obviously she's hung out with him lately. So I called him out on it cause of course he had asked me to check who message him and I looked and it was her. Well the other day he got a message and as a haha I was like who messaged you and then he told me it was her but he didn't reply. WTF! WHY IS SHE STILL MESSAGING YOU? The only reason she would be is if she feels welcome and she's not fucking welcome. Then I was on fb and saw that they became friends again? WHAT?! This is sketchy af. I only know this because it showed up on my news feed. Like I know I didn't delete her because I'm not one to do that unless I see more evidence. But like now I'm thinking they got into an argument or something and she unfriended him and then sent him a request again. Then a while back I saw a girls name in his texts messages but didn't say anything because I wasn't looking for anything he had just asked me to text someone for him so I did. Well then the other day he tells me that him and this girl with the same name as the girl in his texts had dated a while back. Like wtf. Yeah I'm insecure. Idc I've had a boyfriend cheat on me before and hide it for over 6 months and I won't deal with this shit with him. I've never gone through his messages ever but I just have this feeling that I should.