If you dont think you can do it them maybe you should leave it for a while, and it most defo. is not CRUEL I have done it with Dec and it worked well, I found myself crying along with him but he had to be done and now his routine is back.
I do EVERYTHING on my own to, yes I am married but OH works 6-7 days a week then he works a different job Tuesday and Sunday nights so he is hardly ever here, you just need to start a routine and stick to it, if she cries she cries, if you keep starting different routines and not sticking to them she will know she has the upper hand and will play you for all she can, ALL babies are smart little beings and they will try everything to be in charge, you just dont let them.