Mind Game infidelity

Hi I am going out with a guy that is very good with cell phone and he goes Cam too Cam with a girl 24/7 how can someone too that too a person.If the girl talks too loud he cough too let her know and sometimes we can be quite and watching a movie and start talking he anwser her he hides a cell phone he have with her plus sometimes he use is cell phone and he looks at it and makes eyes if I get too close and if he is in kitchen I can hear him talk very low too her as soon he comes too living room he cough too let her .I try asking him but he flip and he said where is the proof u don t have none I being trying too caught him but I am not as good as him on cell phone.i even told him that u know it s not me I don t hear voices or I don t have mental illeness I go too other place and I don t hear whispering or even sometimes he forget lot ke I am around he talks about something that is not in our conversation I am so lost hurt I just don't t know why he will do this too me it s not because of sex because I love that and other things he does with her but pretty sure u guys know what I mean she talks dirty with him and he gets off on it wish I can find app and record him and put it in is face I am so hurt lost and lot going on in my life with him doing this dosen t help I am fed up 😢😢😢😭😭