My kid has RAD and I am really frustrated with him. What now?

This is my first post & I hope this is the right place for this, but I desperately need help right now. So, I will give the back story before I say what is going on so you can fully understand where we are right now. We have 4 kids, 1, 3, 7, 9. We adopted the 7 and 9 year old from treatment foster care almost 2 years ago. Throughout the disclosure process we asked EVERYONE if they had RAD and it was a unanimous no. They said my DS had ADHD, but with my experience as a teacher I disagreed with that. When they moved in with us we stopped his meds and things were great until they literally came crashing down. The social workers kept telling us the kids were worried about adoption and trying to push us away. They said once the adoption was finalized the behaviors would stop. They were also in therapy and she dropped them after about 2 months, saying they didn't need it anymore. Needless to say it didn't stop, but rather escalated. January of '10 we were at our wits end and called an attachment therapist. At the time I was 6 months pregnant and I was worried that I would have post partum depression like I had with my first. I figured the combo of me and our DS couldn't work. The clinical director diagnosed them both with RAD and we came up with a treatment plan. My DD worked through the program and is now for the most part a normal girl. Sometime we have struggle with her, but she is significantly better. Now to my DS. He is not better in any sense of the word. He is almost 8 and has "accidents" whenever he doesn't get his way. He intentionally breaks toys, glares at the other kids in our house, tells my 3 year old scary stories, "looses" his jacket if he is mad, fights at schools, steals at school, breaks school supplies, throws fits, lies, destroys his clothes, pretends like he can't read, pretends to do his homework/ chores/ bath, manipulates people, hurts our dogs, puts himself and other kids in dangerous situations, tries to intentionally injure my 3 year old, took a play knife from my class and threatened kids in his class. And that is the short list. When I was pregnant he threw a fit and started kicking me in the stomach. He also seems to have severe jealousy issues with my 3 year old and it really came to light last month when my little guy had a birthday. My older DS just glared and glared at him when we brought him his new bike. However, just 6 months before my 7 year old got a bike!! To top it off, in November he went and told the school nurse that I pushed him into a dresser and they called child protective services. Mind you, I am a teacher at this school and they knew it was not true. CYFD did their investigation and of course it was unsubstantiated, but I still have to work at that school. I am still so mad that he said that and completely mortified that is on my record. I feel that my anger started at this point. Even though I knew it was untrue, I was still terrified that I was going to loose my babies. I just don't know what to do. I feel horrible, but right at this moment I CANNOT stand him. My DH and I said that when 2 years rolls around, if he wasn't showing progress he was out of here. He has been in attachment therapy since Jan '10 and he is being re-evaluated because she doesn't know why he isn't making progress. I feel like for the safety of my babies and the mental health of our DD that he needs to go. But, we would keep her. We don't feel that she should move from a happy, safe home because of him. I really don't know what I am looking for right now, but had to get that out. People around us see the good, charming little boy and look at my DH and I like we are crazy. Would you call it quits or stick with it? My DH and I are scared about what he will be like in the future if he is already this bad.