Re: leave him??
You have my sympathies chamali. Your FIL is abusing you, plain and simple. It needs to be stopped - most preferably before there are little children involved. Try again to involve your hubby before involving your parents. Explain to him how serious the issue is and that as much as you love him, you cannot endure this type of treatment from your in-laws. The longer he gets away with it, the worse he will become.
You know, I've always admired Desi culture for their strong committment to elders and their total respect of them. But there HAS to be limits here! I've seen some awful, awful situations where an elder was abusive and allowed to get away with it just because they have lived on the planet longer. There is a difference between respect for elders and taking abuse because they're old.
It is in no way disrespectful for your husband to say "Father, I love you dearly and mean no disrespect. But the harsh relationship between you and my wife is a source of stress my marriage and I cherish my marriage very much. If you could soften your ways with her, you would be helping me to make my marriage as successful as I want it to be." How could FIL construe that as disrespectful?