I agree re the parents not murdering her but the hatred they have had to endure is sad all they want is Madeleine alive & home.
I can't say I have ever seen anyone claim Madeleine was murdered by anyone close to her. What has been alleged over the years however is that she succumbed to a tragic accident of some sort and that her parents and possibly others conspired to invent an abduction story. This is certainly the thesis that Dr Amaral promotes and one which the Attorney general mentions in his final archiving report.
To return to the opening question..."Do you think we are to blame?"
No we aren't. That blame ultimately lies at the feet of her parents, her guardians, her protectors. They failed the task and according them some monster took advantage of that failing. That monster, if he exists, is most certainly to blame for abducting her but her parents are to blame for allowing it to happen in the first instance.
Unfortunately, two wrongs don't make a right and Madeleine has most probably paid the ultimate penalty because of it all.