Should I believe him?

Yesterday a girl posted a heart one of his Facebook posts. It was random because I had never seen a girl put anything on his posts before. I confronted him and he told me it's an ex from ages ago, that he doesn't talk to her anymore and to text her myself if I don't believe him. He then blocked her. So I did text her. Tonight I got a reply off her. I asked if she knew him and she said yeah, and asked for his number. I said why? He's ur ex u have no reason to get in touch with him. She just kept asking. Her words were 'just give it me it's not like I'm gonna chat to him I have a man'. I said so then why do you want my boyfriends number so bad? She didn't reply for a while then all of a sudden she got real pissed off and sent a paragraph saying stuff like she doesn't want my man she has her own, that he's old news and I need to stop being paranoid because he hasn't spoke to her in ages. I explained i saw that she posted a heart and he told me to text her so id know hes telling the truth. I then asked again if shes so over him and has a man why does she want his number. She said so she can ask him who I am and why I'm texting her. She just kept getting an attitude with me saying that she doesn't care she's over him they haven't spoke in ages so why am I texting her. Telling me to fuckoff. I just said to her I didn't text to argue I text to simply ask if she was his ex like he said and if they still speak and now I've got my answer let's leave it at that. Apart from all the attitude she basically told me the same as him, that they dont talk anymore and it sounded like she was jealous, or is it just me? I still don't know what to think. I don't get why she had all this attitude. Does it sound like he's telling the truth that he has nothing to do with her anymore?