Monica is so right, your relatives come back for you. My completely rational father started talking to my late mother, despite being due for discharge the next day. He said she was sitting on the end of his bed. He died that night, the hospital were very shocked (and unfortunately even tried to resuscitate him) but she came for him.
I can tell you that you have nothing to feel guilty about, but of course you will, it is part of grieving, along with shock, anger, bargaining, depression and finally acceptance, which is growing around your grief. Many people opt to go when their loved ones are out of the room anyway. You have my really heartfelt sympathy, and I hope you will have the support of your family and can talk together. Feelings of relief that the suffering is over are completely normal too. Lots of love, and look after yourself. x