Am i wrong ?

Am i wrong in asking my fiance not to text or speak to a girl ? Backstory is he works ss a carer in a home of 4/5 disabled people, the girl in question does the same but in a house opposite his. I found out he's been chatting to her and texting ( as friends) which i was fine with but then i got a mystery text saying you need to watch your boyfriend #### is after him. I've seen her flirting, hugging and play fighting with him. She also buys him things..chocolate and McDonalds. She seems to be obseesed with him. I asked him about it and he said yes she did buy him mcd's but she does for all the workers and they were just friends she knows im with you. But i found messeges on his phone( we have acess ro each other phones) which are telling me she could be wanting more.she "accidentally " sent him a picture of her boobs and is claims it wasnt meant for him.one text was im going for a nap do you want to come round and play with my back while I'm sleeping . Wtf! Is that something you ask someone you know is in a relationship ? She's even planning on taking him out for the day ('as friends) shopping and treating him to whatever he wants and buying him a meal with drinks. She constantly want cuddles off him. Calling him baby.My fiance has always been flirty and calling everyone gorgous or beautiful and putting kisses on the end of texts he's always done that im not bothered about that but i am bothered he's not telling her to back off. And encouraging her.I've confronted him about the texts and he said they are just friends I've got to trust him. But From what text ive seen and what i got told about her i dont trust her. I asked him not to text her again. He agreed but i found out he ignored me and they still in contact now all im getting from him is I'm allowed friends that are girls. You've got to trust me i love you I'd never cheat on you. Now he's making me feel im wrong in asking him not to talk to her. Is it wrong of me ? Sorry its so long.