Sterling College interview questions

Did an interview which was a very basic interview question. Got another interview in which I was offered a position and we negotiated the salary. I was promised by email and text that I would get an offer letter in a few days. After 5 days with no response, I messaged the hiring manager to follow up and they told me they decided to hold off on hiring and that she "can't promise me anything". I asked her if that means that she's withdrawing the offer she made to me during the interview. And she replied with a very rude email stating "I will not be sending you an Offer Letter for a teaching position at the college.". I had 3 other job interviews in which I showed no interest because I was already promised a position. Very unprofessional company and I do not recommend working with them.