Praying for peace and strength for you. hugs.
I feel your pain all my grandparents died already i know this is hard for you but just think that your grandma or grandpa already lived their lives and are already old... Be happy and dont stress yourself right now all you have to worry about is your baby and stress does affect your baby in some way.. I bet you he or she would want you to not be sad because its the right thing to do especially now that you are pregnant their time has come they already lived a very long life.. And maybe you will see them some day when you die..
Honestly I don't have an answer or great advice to give... I have lost very many people close to me so I do feel your pain, at the same time there hasn't been any way for me to cope with everything 100% stress free. I think it just hits you differently and at different random times of the day or a certain smell can bring back a certain memory. Just keep your head up, do a lot of stress free things like walks in the park to think, bubble baths, drinking tea, and trying to keep your head up while at the same time knowing it's ok to break down too.