problem with firefox?

i was researching for a project for school, and a site i went to redirected me to something else and an official type window popped up and said i was open to malicious attack and asked me click the button to get a free virus scan. knowing this to be a scam, i hit no thanks" and it says "are you sure? you are open to attack." and at that point i know not to click it, so i go to task manager. something about needing to put something in a certain drive popped up from windows and i just hit continue and closed firefox. now, when i go to open firefox, it reloads the malicious site because i had multiple tabs open and mozilla saves the session and when i try to close out of the malicious tab, it asks if im sure because im open to attack and i know im not supposed to click what it wants me to click.

my question: how do i start firefox without the saved tabs?