Hi Nuttymom, welcome to Bleeping Computer.
Sorry it is under such circumstances, though.
I had Earthlink a few years ago and I'm not sure if it's the same now or not. But, once you connect to the internet, ANYONE and EVERYONE can read email. That's crazy. STOP USING EARTHLINK EMAIL.
Yahoo is not the safest or most secure of the free email accounts available. Go to hotmail
and create a brand new account. Create a password that nobody could ever guess in a million years...something totally off the wall. For example, 'plane22' or 'fall49'. Just be sure you can remember it and use both letters and numbers. Also, it is vital that you set your preferences so that you must ALWAYS sign in and give your password. That way, nobody can gain access to even your account name. Even if you have a hotmail account right now, make a brand new one and let your closest friends know.
At the top of this page, you will see "Search", "Favorites", etc... On the right of "Media", you'll see History. It records each and every page you visit and it saves it by the day and week, etc...
Under Tools (at the very top of this page) and Internet Options, under the General tab, near the bottom, you'll see History. Click the button "Clear History" before you go offline EVERYTIME you are online. Just know that your Address bar/scroll bar will have NO addresses there so you'll have to type out where you want to go each time, etc...
Seriously, STOP USING EARTHLINK AND YAHOO EMAIL, PLEASE. He gained access to your personal emails because they both fail miserably in the secure and safe categories, as you unfortunately found out.
Hope I was able to offer help.