Is It Normal To Feel Guilty?

My little dog Brody has been missing for over a month. She has been gone since Oct 29th. She was outside by the curb with me & my husband, playing with another dog when she accidentally ran into the fence, probably got hurt because she started screaming & running down the street in panic. We chased her but it was at night and by the time we came around the corner we couldn't see her anymore. We've done everything suggested - posting fliers all over, checking the shelter every other day, putting ads in the paper & weekly circular, walking around on the weekend & talking to people, driving around everyday after we get home from work. I've talked to 2 animal communicators, and each time they gave me more hope & keep me going. But I still haven't found my dog. The last communicator told me she seems to found a friend, an old man who feeds her and lets her go inside his house. Although I am still stubborn in my determination to find her and have her back home, I am glad that she is not starving and out in the cold. I just need to find her. She is my baby girl. We have been so happy in the 8 years we've been together. There is no good day since she's been gone, it's like the sunshine disappears and everyday is a dark cloud. I cry frequently and at the most unexpected moments. My heart hurts. My feet hurt from all the walking. My head hurts from the stress and worry and the crying. Since she left I promised her & myself that I would find her, and now that I haven't, even though I am still trying, I feel like a liar, like I failed her. I feel a heavy guilt for failing to keep her safe, for failing to bring her back quickly. I have such a turbulent mix of feeling and emotions and everything seems worse because none of our friends or family save my oldest sister-in-law have offered to help and they don't even seem to understand how important she is for us. I know when people tell us "she probably got picked up by somebody" or "oh, dogs are resilient, she'll be fine" they're just trying to be nice....but it sounds dismissive, and I'm not sure how to respond. I'm sorry for the long post. I just need to get some of this stuff off my chest. I hope you don't mind.