One option would be to go to your doctor and get signed off as sick for the notice period as a consequence of the stress caused by your employer's treatment of you. That way you are not leaving early just not well enough to go in and it avoids confrontation.
The alternative would be constructive dismissal. This is where the employer treats an employee so badly as to breach the implied term in the contract that you will be treated reasonably and with respect.
This way you inform the employer that they have breached the contract as a consequence of treating you badly and, as such, you are entitled to leave as you no longer have to abide by the contract as they broke it.
I hope this helps.
If there are any further points please reply and I will be happy to respond