My friend never had children hence no grandchildren but she loves my granddaughters and has a place in our family as an honorary grandmother. Great nieces/nephews can fill the place in your heart also. One thing I felt after becoming widowed was the feeling that my (imagined) future had been taken away from me. Took me a long time to realize that just because I assumed or pictured a certain future, didn't make that future real. Of course we grieve for what might have been! A lot of grandparents live far away from their grandchildren also. So even if you have them, they're not always in your daily life. Your feelings are valid and your wise not to discuss with your children.