Generally, the lender will not take into account "boarders"/ roommates- even though that will help you out in reality. So, you'll have to qualify on your own.
You have excellent credit- so that is good.
On a $80K yearly income, my ballpark of the most you would qualify for is a $325K loan. You would need to put down at least 3.5%, for an FHA loan. My guess is you could find something in Burlington, or Woburn, for that price for a 3 BR place. If I can help you any further, please call or email me.
Thanks and good luck,
The lender will take into consideration the rental income of the condo, although the -$800 hit you will take will lessen the amount of home you will afford. I can easily pre-approve you, at no cost to you. At that time we can discuss your income from your house mates.