everyone is perfectly capable of being in purely joyful state all alone by their own. If someone comes along then its great, the joy multiplies. Because then neither of you will exploit the other. You are already happy on your own, there is no need for exploitation. And the people you will attract will be equally independant. They wouldn't exploit you for your money and you wouldn't exploit them for their body.
If the right one comes along your joy is multiplied. If not its fine. You are happy on your own.
I suggest that you meditate over it. Go sit down, think over the situation. There is no reason to be sad. She is no more, but the sex wasn't making you any happier. It was just a diversion. It was like watching Tv when you are bored.
The diversion is no more. It is a perfect oppurtunity for you to look deep inside you and find joy, that needs no cause. Because it is in our nature to be joyful.
I hope you tackle this well. My best wishes are with you.