Drama

So I need advice on March 7th I had sex with my ex (he’s the one who took my virginity) I texted him 2 days later and he said “you got me in trouble” I said “with who” he said “my girlfriend” yall when I say I was soo shocked and caught off guard...so I replied like “how long yall been together” he said “a year” so I cut all ties with him...in April he texted me “goodmorning beautiful” then the girl slid in my dm’s trying to argue but im a positive person so I just kept sending emojis and she found out where I worked so in june she started coming up there “looking for me” trying to fight even though her dude is in the wrong so I texted her like “im not going to fight you because he cheats on you I didnt know you existed and I’ll never fight over a man” then my sister texted my ex and he was like “I didn’t know she was coming to her job she’ll stop coming up there and texting her” and she hasn’t since but the boy has like 30 bodies I just dont think its smart to fight over a boy who literally has sex with everything oh and he gave me chlamydia and she doesnt know what should I have done ??