I have sore feet and right diagnosed with mortons neuroma so is a stationary bike ok to use for exercise or will it aggravate the condition?

Yes. Provided little or no pressure is over the forefoot or over the neuroma, you should have no problem. If, however, while doing the exercise, or the next day, you have pain, then you should listen to your body and modify or discontinue. Cycling, if done properly, should not aggravate a neuroma.
Neuroma. A neuroma is a painful benign impingement of a digital nerve in the foot. It usually can come from some trauma to the foot including wearing tight shoes. A stationary bike should not irritate the neuroma as long as you are wearing good sneakers with passing on the sole. Don't wear thin soled shoes or sneakers. .