Please help me im confussed..?

ok so my boyfriend of 4years and father of my 7month old baby has said hes not cheating but why did i find texts on his phone from a number saying `be straight with me do u want to c me again` and `can you ring me` and sorry for ringing you at work but do u wnt to c me again for a good ?????` surely them texts mean hes cheating plus i found in recored ur own sounds that there was people having and the sounds theere were about 10 different ones now is that hes recoreded off a film or he made them~~ please help me i feel like im gong to breakdown its destroying me ....i cant seem to believe it wen he says hes not cheating