Hi. I'm Brian and I will do my best to help you.
Do you each have separate Windows accounts? You should. then you won't have data access conflicts.
That said, you should be able to add another account to Outlook that is for your mailbox, provided your company allows outside access to the mail server. When I was working and needed to access my company mailbox, I had to connect via a VPN in order to access the mailbox. My advice, though, is still for each of you to use separate Windows accounts so there's no accidental data transfer. Companies don't like that.