We went to the clinic today and my dog have a virus that effects the dog and now we are trying our best as it is serious and I'm not sure if I should tell the seller as there were dogs together and it could have spread

Without question, you should tell the seller. Early treatment of the dogs/puppies exposed, gives them a better chance at surviving. The seller will also need to know so she can clean, disinfect, all areas to prevent future exposures to the virus.

I hope your puppy makes a full recovery. What is the name of the virus?

The seller, if they care at all about there dogs, will want to know. If they don't take interest in any illnesses their dogs have then they shouldn't be breeding. Others who have bought dogs from this person need to be notified as well so they can have their dogs checked. A good breeder would pay for treatment of dogs they sold with something gained while still in their care.