I completely understand and you have my sympathy! I am in a very similar situation. Only it's my husband and he drinks alcohol within the first hour he wakes up till 1am. He is unemployed and will not work anyplace beneath him and I could go on. We have 6 year old triplets so that complicates throwing him out.

I would get him out of your place. You guys aren't married so no expensive messy divorce. He is not your sons father and your son is older so he would probably be extremely relieved if bf moved out. I bet the tension in the house is extremely high. Think about the $800 like a present for yourself and your son not for your bf. If you had dangerous black mold or a poisonous gas leaking in your house wouldn't you pay $800 to get rid of it for you and your sons health and peace of mind?