If interim alimony is already allowed by lower court, then no use going to HC. It will be waste of time and money. And you will have to pay the old dues first, clear them. and then you can approach HC stating change in circumstances and ask them to readjudicate such interim alimony awarded.
Remember, such interim maintenance ordered holds good only for a period of 1 year. After a period of 1 year your wife has to submit new application asking for interim maintenance and at that time you can also state in your reply to her IA application that your circumstances have changed and that you cannot pay what you used to pay previously. Here you should submit to court your income - expenditure [with bills] = take home salary. Based on that IA will be calculated. Suppose if your wife does not file a application of IA each year, you can go ahead and file your change in circumstances applicatoin in the lower court itself asking them to reduce the alimony awarded. When they say no. You can approach the HC and they will reduce the alimony accordingly.
At the same time you should also produce evidence regarding your wife's education, ask for appointment of Court Commisioner in order to ascertain her immovable assets and income from those assets. Provide information to the court about her employer details. Then after looking at her income and your income [minus expenditure] alimony will be decided. in absence of all this, whatever your wife has asked will be ordered as alimony.
Am sure you have failed to reply to your wife's IA application so you are in trouble. Change current lawyer, engage good lawyer.