how safe is it to access something private through opera mini?

I don't know a lot about computers or data or what is opera, for me opera is a way of singing, but what I know that I had a boyfriend in 2006 who used to work in a call center like making money gram or sending money from people of one country to another,then one day I was in his office and he didn't have money to buy a calling card to call a taxi to take me home, what he did was he went like to wester unon and I don't know what happened but was like he couldn't do it then he enter to a paypal of somebody, I was surprised , then he told me that he have access to the credit card or pay pal info of those people who used to send money online.or by phone.