Resentment towards siblings who won't help with elderly Dad?

My Dad is not allowed to drive now, but since I am living in the same town, now I am responsible for taking him to his coffee group, the store, post office, etc. I have two siblings who do not live here but could come take him to the doctor or help with other things and tell me to "think outside the box" or other little hateful remarks. I don't want to have anything to do with either one of them! I am trying to forgive for things they have said and done in the last years (way too much ugliness to list here done not only to me but to my kids) I am accepting that I am the caregiver, yet I am not allowed to speak to the doctor (my sister can, but I can't) I am just the laundress, housekeeper and taxi! I have basically quit working to take on this mess. My Dad can see to walk down the street, but can't see well enough to sign medical papers at the clinic for his meds. (Through the VA) I am at my wits end about all of this. I feel guilty not working, but feel guilty not driving him to coffee. How do I get through the resentment?