I am right or wrong

I am having an argument with my girlfriend and I need an outside opinion. I bought her a pair of boots but got the wrong size and cannot return them and when I toldher this, she suggested that her mother might buy them. I said ok great, I will bring them over for her to see. Meanwhile, my girlfriend spoke to her mother and her mother said she would probably buy them. I was a little surprised because I knew that she liked a different pair more, but agreed anyway because I really wanted to sell them. So the next day, before I brought them over, I had a chance to sell them to my sister who really liked that style, so without letting my girlfriend know, I sold them to her. The reason that I did not discuss this decision with my girlfriend first is that I had found a place to get the boots that her mother really wanted so I thought they would be happy to get them instead. when I got to the girlfriends place I told her what happened and was not apologetic, did not care that it bothered her(her words, I really did care), and did not think she had a right to be upset and that she was being illogical. But then I found out that her mother was planning on returning her other boots today and now will have none for now and now the girlfriend is not wanting to tell her that she has no boots.

Hi Darkel, if your sister gave you the same money that you paid for the boots at the shop, could you not but another pair the same and sell these to your girlfriends mother? I know your girlfriend will still be annoyed, but you could discuss this option with her, since her mother doesn't know about your having sold them already. The only problem could be that her mum hasn't seen the boots?, and that they may actually not be suitable for her. Getting sizes of clothing right for other people can be a nightmare, be creative with how you handle this - I think you'll probably have to apologise to your girlfriend before anything starts to get better. You never know, she could be over-reacting and your mother may be pleased that she hasn't got to take the boots of you anyway - that way she gets the boots she really wants, right?