Someone is hacking into my email?

Question

I sent a mail to a friend of mine yesterday and his parter foundout about it, she then somehow hacked into my system and forwared that mail to everyone in my mail box this morning. She then phoned and informed me, when I checked it was true. There is no how she could have know my pasword because I rarely use this email and had to try several times to get it right yesterday. How was she able to do it and what can I do to prevent it happening again. This person also tried to add me to thier yahoo chat on my other yahoo address and i declined.
I am really worried, is it possible that she can get into my pc or is only my mail that is affected. Please help

Answer 1

I don't think she got into your PC, and maybe not even your mail, but I suggest you change your passwords anyway.

I think she got into your friends PC and your friends mail. Then I think she looked at his mail 'Recieved' folder and found out your mail.

Then I think she clicked 'Reply All' and it copied all the addresses from your friends PC.

When you send a Mail to lots of people, every-one who receives that mail can see all the addresses of all the other people you Send or CC: it to.