I fear my ex put a spy ware on my computer. While talking to someone on messenger on Facebook they said my ex knew everything I had written and not by anyone telling them. I downloaded AVG Antivirus and it found 3 trojan viruses.
It is literally impossible for any program or utility to guarantee the absence of such malicious interference. The only possible result of an in-depth examination of your Mac would be to identify the presence of a keylogger or similar eavesdropping software. However, consider the following hypothetical result if you were to find such a product installed. Upon careful research you subsequently uninstall it, and conclude your Mac has thereby been rendered secure. Meanwhile, your ex planted additional software that isn't as easily discovered, and it remains active.
Nothing short of erasing that Mac completely and reconfiguring it as a new machine should be acceptable to you. However, even that cannot guarantee the absence of hardware devices that can effectively accomplish data theft. There are also countless, but less technologically involved ways of eavesdropping, and they don't even involve a Mac.
"AVG" will do absolutely nothing beneficial and will only cause other, unrelated problems. It may also prove difficult to uninstall. Besides being grammatically incorrect, its uninstallation instructions do not work, a typical characteristic of garbage software. Don't Google anything and don't install anything. Your problems are not going to be solved by doing that. They will only make things worse.
In light of that information, perhaps you should reconsider your question and ask for appropriate guidance. Bear in mind that unauthorized use of someone else's computer is a criminal offense, and has been for many years.
