Ok, this is coming from someone who also has tons of lease experience and lots of critters. Not to be rude, but I wouldn't even give them 30 days. Get them out NOW. This has gone WAY beyond a helpful hand to a friend.

A) As Joanna said, one emergency not even in your unit and you're sunk!

B) They have done more then taken advantage of you...they've walked all over you with muddy cleats!

C) Friendship is TWO sided. These people do Not sound like friends...more like moochers in paradise.

Do what's best for you, your fiance, and your animals and get them out of there ASAP! Be firm and state your reasons, both legal and personal, calmly. If they get all upset just stay firm.

Good luck hon!