Cheaters ? Do they change

Lisa • I`m strong because I have to be.
I have a bf who has cheated on me a few times we are together we have a 5 year old together, he claims he won't do anything to ruin our family but I found porn on his computer... I'm not against porn but it's skinny girls... I'm not skinny but I'm just a little bit more then the average.. And I found a web cite called arrangement finders in his junk mail... Does anyone know if guys really do change? Or do I need to move on ? In puts are more then welcome on advice thanks