The couple ended their five-year relationship last week, with reports suggesting that their hectic work schedules put a strain on their romance.
"I wear my heart on my sleeve and it is hard to hide my emotions," he told Sky Sports News. "I try my hardest to be positive. I am going through a hard time at the moment.
"I have lost someone special in my life and my world has been turned upside down. I am trying to pull my stuff together and keep my head up which is so hard to do."
Hamilton finished fifth in the German Grand Prix yesterday.