The Jedi couldn't help Anakin cause he was so secretive, he never told them that he was going to see his mother before she died (EP II) so he didn't have guidance in that respect, revenge could have been avoided. Anakin told Palpy about his revenge, and Palpy encouraged it, letting him know that its ok to take revenge, eg, Dooku.
Anakin did one thing right to talk to Yoda. Yoda told him to train himself to let go of everything he feared to lose. But, he failed to do so. Palpy corrupted him more by telling Anakin that he can save Padme, so the jedi teachings went out the door.
The Jedi had the right to not trust Anakin, they could sense much confusion in him, the jedi knew Anakin been through alot. Anakin could have gained Maces trust if he stayed out of the Palpy situation. Its a touchy subject for the Jedi, when the Darkside of the force surrounds the chancellor, and Anakin is always by his side.
So, I dont think the Jedi were to responsible because they did what they had to in that situation.
Mace was orignally going to arrest Palpy, but Anakin got in the damn way and led Mace to believe that he must be killed, so Anakin held some part in that.
Hard decisions to make, even for Jedi