Roommate moving out

So my roommate is planning on moving out this fall before the lease is up. My therapist says he doesnt need to pay the rest of the rent till the lease is up because he has given enough notice. My mom is saying since he is breaking the lease he needs to pay the fee for breaking the lease and I should sign a new lease since I'll be staying. I'm a bit conflicted since it's true he has given pleanty of notice but if it was just him renting he would still have to pay the fee for breaking the lease. What are y'all's thoughts on this? Should I insist on him paying the rest of the rent/pay the fee for the lease, or let it go?