Should I tell his girlfriend?

Ma

So I’ll make this simple. This guy I was friends with back in high school who I haven’t spoke to in like 7-8 years added me on Instagram then fb and we talked a bit then he messaged me tonight and this is what was said

Do you think I should message his girlfriend and let her know he’s doing things like this or stay out of it

UPDATE

I do know his girlfriend and I sent her the screenshot saying it might be none of my business but I know I’d want to know if my boyfriend was over stepping boundaries She opened it said thank you. This all happened at 9 at night. The next morning I wake up at 7 am to my phone going off he’s calling me over fb. My husband deal that phone call because when I answered it (on speaker) the first words I heard was “BITCH!”

I saw his girlfriends fb post saying she’s single now and a post saying dogged a bullet so I guess I did the right thing 🤷🏼‍♀️