I need an advice PLEASE

I am having some problems with my ex- husband last couple months via emails or texts. He was always rude man , mentally and physically abused me 7 years . I divorced him 4 years ago and now I am married again . My ex husband always tried to find my mistakes and use them against me. My husband   keep telling me I need to save every text , emails and write down every conversation in journal between me and my ex-husband  so in future I can use them if I need it.
Well , today I saw an email in my husband's computer. He has been doing the same thing he was telling me to do for my ex-husband . He made a list and sent it to his self also the email is in draft file so he can add everyday before he forgets.He has been writing down our every fight, argument, date and even what time it happens. I haven't told him I saw this email .He knows i am having hard time trusting people after my first abusive marriage. He tells me that he would never hurt me like my first husband did but now I am thinking he will use this list against me one day. 
What do you guys think? Why would he do this? 
Thank you.