You ought to be suspicious that the purpose of the freezing out is to cause you to become so frustrated that you resign and walk away.
Should you do so, you probably have no legal recourse against the employer because Fair Work Australia has a very restricted view of constructive dismissal. The company may be hoping to avoid paying you redundancy.
If you become so stressed that you need sick leave then you would be wise to take sick leave so you can recuperate because if not you might do something that you regret. For example you might do something at work that could cause disciplinary proceedings to be taken against you.
If you can see no future with the company you may wish to commence agitating for a redundancy payment on the basis that your position has become redundant and no suitable alternative position has been offered. Agitating for a redundancy is not something you should embark on without strong legal representation.
Your position can be made redundant even though the tasks you were doing are still being performed by other employees. You are entitled to a minimum payment under the Fair Work Act for your redundancy, however your employer may have a more generous redundancy policy in force. Your employer is unlikely to categorise your position as redundant as your entitlements may be quite costly to them. It may be easier to negotiate a financially better payment if you remain employed, and it is crucial to seek expert legal advice.