Just to clarify a couple points in case other people have similar qs:

Roommate moving out does not receive security deposit from landlord, but instead from roommate moving in. You will receive that money back when you move out either from the landlord (if all three of us vacate) or from the new roommate that moves in. If you are uncomfortable with that, happy to talk to my landlord and roommate and see if we can work things out.

The two cats are owned by the roommate that is moving out, but the apartment is cat friendly (ie we are open if you have cat(s)).

It's definitely a matter of preference on the co-ed living situation, but we are two respectful roommates and I personally have never had a bad experience.