Letting tenant out of lease + adding turnover fee

[Tina Rubin]

We have a tenant (RI) who has rented out a room in a shared apartment that would like out of their lease early. We are ok to allow this but want to charge a turnover fee which would equate to the same amount as the security deposit. I know the security deposit can only be used for damages so legally do we need to collect the fee from tenant prior to vacating?.

We're also wondering if we put in writing the following and they agreed via email if that's sufficient:

#1 they are still financially responsible until we are able to rent the space

#2 we're charging a turnover fee $1k to let them out of the lease early and collect that immediately

#3 security deposit will be returned according the the RI tenant laws (ie place is left in same condition as move in)

#4 room is made available at reasonable hours for showings/open house

Or do we need to hire an attorney to provide a lease addendum stating an early termination fee?