What to do if I live in a college house with 5 other students but state law only allows 3 people to be on a lease?

Just as a note, occupancy restrictions are usually placed by community/city ordinances, not an overall state law.  What your friends think is the law in your city, may be correct for one town, but not another.  If this is just your friends telling you that you have to leave, check with the city first to see what their ordinances are regarding occupancy restrictions.  All of you may be stressing for no reason.  If the landlord isn't telling you to move, then don't.

If there is an occupancy restriction, your first step is to review your lease.  If you have a valid lease agreement, you don't have to leave unless you just want to.   The three who are not officially on the lease need to be the ones to leave.  If everyone is on the lease, then the last three added should be the ones to leave because they are the ones that were technically added in violation of the ordinance.  If you were one of the latter three added, you can still fight to stay-- at least to buy you some time until you can get a new place to stay.  Your contract will provide your remedies.  If the landlord concedes that they added you in violation of the ordinance, you should be able to get your full deposit back which would give you some funds for finding a new place.  If you and the other roommates cannot reach an agreement, you do run the risk of the landlord filing an eviction suit against three of you.

If you are not on the lease, you have far fewer options because the lease is what gives you standing to fight for your spot in the house and to demand the return of your deposit.

If you can get three others to move out, that would be the ideal situation.  As a backup, you do need to start looking for alternative housing.  You mention that you are in a "college house."  Consider contacting a dean to see if they are aware of any inexpensive housing options in light of your emergency situation.

As far as what would I do.... I did have an experience in law school where I could not live in my apartment for while because of a series of burglaries.  I moved most of my items to a rental unit and slept on the floor of the college library or my church at night.  (We had units in the library that were easy to duck under).  I'm not suggesting the same exteme actions for you, but just keep in mind that there are usually options other than missing school.  Your college education is too important to throw away.  If this housing doesn't work out, get creative in looking for other options.  For example, the law says that three of you can't "live" there, but there is no requirement that you can't show-up to just use the shower.  One of you may be able to find a place to crash-- but still use the college house to refresh in the morning.  I know this is stressful--- but don't let it deter your college goals.