First you have to keep going. Despite guidelines and consensus on good teaching practice there will always be those who disagree with methods, although you don't sound like you were doing anything radical or irresponsible. Getting handouts right takes practice and any teacher worth their salt should continually gauge their effectiveness and be prepared to amend if necessary. The college's actions are certainly irresponsible. Teaching is not an easy job and few of us have reached the point of being "very good" or "excellent". We must support each other and share experiences to improve through community not isolation. You will find a college with this approach. Those colleges who don't support staff will eventually fall foul of the system.