any advice please!!

So my boyfriend of 7 months and I are great except the fact his ex will NOT stop. She has messaged him saying she doesn’t know why she broke up with him etc multiple times, she showed up at his church today to show him she’s changing ( she broke up with him btw to sleep/date his cousin ) he swears he’s over her and my last relationship was basically the same thing except I ended up getting cheated on with his ex & they got back together. He doesn’t understand why it bothers me so much. I honestly don’t know what to do.. I love him and I want us to last, I just wanted to know if anybody else had a similar experience and got past it?