Fake girlfriend or real? I can't be sure.

My bf just left after five years together, we broke up in June, We were about to buy a house and then he found out his job was at risk and his personality kind of switched on me. Suddenly he didn't have feelings for me anymore and pushed me away. He kept saying comments about wanting to be alone and just wanting to be away for work now and relying on himself.begged and did all that and got ignored.Went round there in the end and he was jaw dropped to see me.tried to give him space for a few weeks then reached out.Our main source of communication was Whatsapp due to my phone signal, but he hates apps and social media etc.Start of August, he has set a picture of some new girl as his whatsapp picture and ignoring me.It is a girl on her own and doesn't look his type at all. He is very quiet and she looks very social and doesn't look like she lives local. The photo looks like it's taken on an estate at flats and standing next to a box of cigarettes but he is very strongly ashmatic. I have no choice but to move on. Heartbroken. Many are saying the picture is likely to be fake so I react, it breaks my heart thinking of him with another woman. I reached out and got nothing. I don't get how he went from looking depressed etc to suddenly pulling a girl in the space of a month. There was pics in July put on their work fb page and he looked unshaven and like he let himself go. I can't get my head around the feeling it's fake. I just don't know what to do.