my boyfriend never claimed me as a girlfriend

Hey guys so recently I was in a relationship well thought I was in one but then I realized he started to change up on me and I had told a friend about it like the guy didn't text me as much he was always busy and when someone said oh he's cheating I would defend him so like I said I told a friend about it and she said I should download an app called TextNow and pose as a female and and text me so I thought about it and said okay so last night I finally tried it and I asked him if he was single and he told me/her "yeah I've been single for a while the only thing I ever dated was my books." Now I don't know what to do as far as confront him about it. My friend thinks I should keep it going and then when he wants to meet up show up and confront him face to face but I think I should screenshot the texts and confront him like that... what should I do?