worst mother in the world

I'm trying to get my LO to self sooth, but she is fighting it. She hates to nap and will scream of and on for an hour when I try to put her down. Yesterday her screams reached a level where now she has lost her voice and everytime she makes a peep (happy or sad)  I feel like the worst mother in the world. This coupled with 4 month sleep regression I don't know what to do!