Hm.. I'm not going to lie. This is going to be difficult. Your first concern needs to be safety for your kitty. Also stress.

It will be very important that the kitty have its own areas of the house that the dog can not access at all... use kitty doors or baby gates or whatever the dog can not cross. That way your kitty will have areas it can escape to and feel safe.

When cats are stressed, we can see behaviors such as hiding, but even worse, on top of that, we can start seeing problems like inappropriate urination or defecation outside the litter box. You want to make sure the litter box is located somewhere the dog does not have access to, as well as the kitty's food and water.

Do NOT force introductions... let them work it out. Do NOT leave them unattended together. If the dog is not crated or closed in a room, then enclose the cat in a room with its box, food, etc when you are not home.

This will allow them to get used to the idea that the other one exists but does not force unwanted interactions or heighten stress.

Are you moving in with him or is he moving in with you? Or are you moving somewhere new together? Cats get much more stressed about new living situations and travel, so I wouldn't recommend taking the cat to the dog. You could bring the dog to your kitty's house, but don't push them to interact and make sure the kitty has an out...