If my antivirus had a conflict with Firefox, I'd get another one. I use Defender with Windows 10, AVG with 7 & 8, and at home I use Norton because I get it free from Comcast. I know from experience that these work with Firefox. There are other browsers besides IE, Firefox, & Chrome. Windows 10 has Edge, but I'm not a fan of it. There's also Safari from Apple, a browser called Opera, and others as well.
I have been having trouble with Mozilla Firefox as there was a conflict with Kaspersky Internet Security. I ended up removing Kaspersky and downloading Avast Free Antivirus. Now I would like to find a compatible browser. Not IE, and I'm not familiar with Google, any suggestions?