It takes billions of times more energy to create antimatter than it yields from reactions
... and only the fusion process is clean. It produces little or no waste during operation, but huge amounts when the reactor is decomissioned. The fusion reactor is gigantic, like 100 feet tall, weighs tens of thousands of tonnes, all radioactive.
I'm not certain what the mass of a fission reactor is, and how much radioactive waste is produced when it is decommissioned, but it is significant for a fusion reactor. In fact, I'm going to look into it and get back to you. May as well make a fair comparison...