Washington state tenant I want to break my lease?

I am 6 months into a 12 month lease here in Washington state. I recieved a layoff notice from my work and my wifes unemployment expires in 2 months. The lease i signed says that I can terminate the lease by giving a 20 day notice. And i will forfeit half of my 1195 deposit for terminating. They "may" also charge me extra fees or rent up until the end of my lease term which is another 6 months. I will be sending them a certified termination letter 40 days in advance stating termination and the hardship that we are having. Are they liable to charge me till the end of the lease term or what do you think will happen, what is the law? when i signed the lease the lady said with a 20 day notice i will only get charged half my deposit. but now reading more in depth i "may" also be charged till the end of my lease. Can someone explain the law to me and stuff