Some people just react to var by retaining water. Just how you respond to it. It doesn't aromatize by nature, so its not that. IMO its really not the right appproach to try to use winstrol as an anti-estrogen. As I said, var doesn't aromatize so there's no gain to try to use an anti-aromatase to suppress what isn't happening anyway. Further it is still a steroid so steroid + steroid = more steroid. May be too much steroid.
Its frankly not that bad, so it should be something you can work around by modifying your diet or just deal with it. If you're cutting for a competitoin, then stop the var 10 days out so your body can flush the water before the show. If you're not cutting to a show, a little water isn't that big a deal.