What is the jail sentence for assault in washington state?

i had my boyfriend arrested and he is charged with 2nd degree aggravated assault im just trying to find out how long he is going to be in jail. im getting a lot of different answers, he has a prior felony that happened 20 years ago. i cant find answers i either getting 3 to 9 months, a couple years, not more than 10 years, then 25 to life i really need an answer i want to drop the charges but they said it is up to the state and i cant do nothing about it. and also we had an apartment together my name is on the lease and when this happened he got evicted so since my name is on the lease do i have legal right to keep his stuff? all im trying to do is pack it and store it. am i allowed to do that. or does all his belongings go to the trash. he also has a car. please help me....... i am currently staying at my dads house and i dont have a key to get in.