You have a bladder infection. If your partner has an infection of the prostate I don't know if he could infect you or not, best to ask the doctor or nurse. It isn't a sexually transmitted thing so although I can't guarantee your partner isn't sleeping around - this isn't the result of sex outside the relationship.
Cysts are fluid filled growths located on different part of the body, often attached to organs such as the kidney's, liver, ovaries, etc. They are usually benign and harmless although some are cancerous. But I don't think you don't have to worry about that.
Taking cranberry pills will help prevent future outbreaks. It makes the lining of the bladder less able to host bacteria. Cranberry juice has too much sugar, and you would have to drink too much, for it to be of any real use.
As well the antibiotics may give you a yeast infection as they can kill off the good bacteria in the vagina. After the antibiotics are done, taking acidophilus (health bacteria) pills will help restore healthy balance (don't take them before the antibiotics are done as they will fight against the antibiotics) As well you can get an OTC treatment that is a medicine to clear that up. Thought you may appreciate knowing this may happen.