What to do about my landlord?

I never saw a bed bug before... until my neighbors moved out. I had done some work cleaning the apartment above me for my landlord. when I went up stairs to clean it was infested,roaches- bed bugs... gross I told my landlord about it he claims he went up there and bombed...but diden't bother to mention to n-e 1 else in the building about the bombing.(He only bombed 1 aptment...left the other 3).or the bug problem we all have kids, I don't think he was even supposed to exterminate while ppl were home! I moved in 2 yrs ago... never saw a roach, spider, or bed bug until yesterday ... this is kinda gross...but i kept feeling something in my paint leg...I lifted my pant leg but all that was there was a slightly swelled reddish bump...and Itchy! I went into the bathroom and removed my pants and flipped them inside out and inspected....just what I thought a F******BUG I was pissed off cause I know my landlord is cheap and won't take care of the problem, WHO do I call about this and how do I make it his expense and not mine cause b4 I moved in I diden't have this problem...It wasen't till he started renting to dirty ppl..Now im just seeing more & more everyday me and my kids are getting bit up and I can't take it no more...please help..what to do..I tell him and he says there isent n-e thing he can do about it 2day cause he's busy...so maybe when it comes time 4rent im gonna be busy too..lol..