Did i mistreat my pet?

Honestly for me, tying a dog, not providing it with proper nutrition, injections, medicines, training and enough time to walk and play with her is considered as cruelty. However, do not feel too bad since you now have learnt your lesson. It is ok to miss her ofcourse and feel bad but why don't you channel this into something more positive like donating to your local SPCA to help homeless dogs, volunteering etc. After all your dog was able to make you realise how to love and care for animals. I think that is what our pets are for anyway. They'll provide unconditional love during their life so that you can love and care for more animals in the future :D