friend turned boyg turned roommate...need advice

oops the title should say boyf not boyg. lol anyway...

i need advice. in july, after my now ex (whom my kids and i are still living with) wooed me back (he duped me is more like it...he made himself look reallll good to what i'm wanting in a relationship if i have one) impulsively moved in w/ my friend of 8 mos. we'd dated on and off briefly (and i mean...briefly. i always broke it off as i felt no real connection on a sexual or friend basis) and my two kids ages 9 (dd) and 4 (ds) who have known him all the while as we have done lots w/ him like sledding, rollerskating, eating out, movies, etc. so he is like a family friend.

i want to keep this purely roommate-ish now until i can save to get out. i'm not working...yet. (working on that) and don't want any romantic involvement nor to make this seem like we are a family, which is what he wants with us. i don't even wanna be his buddy or companion anymore. i can be civil but i want my kids and my time to be OUR thing...not him imposing on our goings on. they are my family. not him. i don't know how to express this and we've been avoiding communication. it's very uncomfortable. but he will play with my kids...mostly my 9 yo dd and i can't stand the attention he gives her compared to me or my son. it's made me suspicious. any suggestions on how to lay it out, now that i've changed the dynamics? (we are in HIS rental...he rents from his step dad and mom...i pay half of the rent...it's all i can afford right now as i'm on state assistance for my family)