Please take care of your emotional well-being and give your daughter-in-law a telephone call or better yet, tell her--preferably in the presence of your son--in person that you would like to be notified personally when/if your grandchildren have accidents or become ill.
Not sure that's a good idea, the daughter in law might resent being told what to do. She will do as she pleases anyway. Better to just let them know you are there for them should they need you.