Wow I think your inlaws are worse than my FIL! The only difference is my FIL will think all of those things about me, he's just too nonconfrontational to say them.
First off, I know my hospital has a limit on how many people can be there for labor & delivery. Do you know if your hospital has similar policy? It might be worth looking into to try to pass the blame to them a little bit.
Secondly, I would advise you to sit down and talk with your DH, and tell him that HE needs to be the one who handles relationships with his family, and in an honest way. If you lie, and they find out, that could just make things worse down the road. But anyway, I know with my own DH I had to talk to him several times about the fact that I need to KNOW he'll stand up for me if it comes to that. That the family we created by getting married takes priority over the one he was born into, plain & simple. DH isn't the most confrontational person either, but I've learned that he just chooses his battles. Things came to a head once with FIL and DH really took a stand for me. Your DH needs to pick his battles too. He doesn't need to be like his family and be so constantly in their faces, but I would say that this is a time that he needs to man up and let them know that the family you two are building takes priority. That whether or not his family thinks that you are to blame, the fact is the two of you make decisions together and he supports your wishes about the baby 100%. HE needs to make a stand.
Trust me, from what I've gone through with my ILs (mainly FIL) and DH, I really do think that HIM standing up to them will be the best. I know that if I confronted my FIL it would just make things worse in the end, confirming in his own twisted mind that my attitude/personality is all to blame, etc. It's hard to be patient and let DH take the lead on it, as I'm definitely not afraid of confrontation and wouldn't have a hard time telling FIL exactly what I think at times, but it's definitely much better received coming from DH instead of me.