Should I confront them?

There's this girl that I've know for I don't know how long and I've always hated her guts. Whenever i got a boyfriend in high-school at some point she would start messaging them and flirting with them (didn't go to the same school). Now I'm married and she's in the picture again. She started working at the same place as my husband and he knows how much I hate her. I've asked him not to talk to her and I've caught him snap chatting her and I blew up about it. He stopped talking to her, blocked her on facebook and snap chat for a while, but now they're talking again. I saw that he added her back on facebook and he said his Facebook was just messing up and he deleted her again. But I got on his Facebook and saw messages between them and she said she loved him and missed him soooo much and he told her to add him on snap chat. He doesn't know that I can get on his Facebook and I could also get in his snapchat. So I'm not sure what to say to him or if I should confront this girl. I'm so beyond pissed off