My 18 month old cat was diagnosed with leukemia today. Anyone have experience with this?

Timmy, my beautiful, gray tabby that I just adore was diagnosed with feline leukemia today. He has been sick since about Friday, but we didn’t realize how sick until last evening. We took him to the vet on an emergency appointment the vet was closed, he came in to see Timmy. He is lethargic, has lost a lot of weight, is running a fever and generally just not himself. They didn’t do blood work on Timmy, but my friend had adopted Timmy’s sister and she had to be put to sleep due to leukemia. The vet said more than likely, by the looks of him and his symptoms and fever that he has leukemia also.

The vet put Timmy on some antibiotics and told us we needed to change his food. I was really upset and kind of shocked, because I thought he would have to be put to sleep if he had leukemia. I didn’t ask a lot of questions. The vet said that Timmy would just live with the leukemia. I have two other house cats. I’m frightened they are going to get leukemia also. They were vaccinated when they were kittens, and my husband says they are fine and won’t catch the leukemia. I’m not entirely sure he is correct

Have you had any experience with this kind of situation? What should I do for my other cats? I will call the vet tomorrow when he is actually open and I’m not as upset, but I wanted to ask the jellies their thoughts and opinions.