Blue Quaker laid an egg after 9 years

We have two Quakers. Our green one (Petey)is 19 years old. Our blue one (Peeko) is 9 years old. We are not sure if Petey is a male or female. We are sure that Peeko is a female. Anyway, they have always had a love hate relationship. Petey generally does not like to be bothered. Peeko loves Petey (and pretty much everyone) so she is always trying to hang out and take over his cage. Sometimes this led to a little nipping at each other. Anyway, we left on vacation for a week. We had our 19 year old return home to feed/check on them. Anyway, when we got home we found out during the last check he left the lights on!! So we were upset about that. The next day my hubby noticed our two birds in like a mating position (which never happened before). Then he kept seeing Peeko squatting over Petey’s dish. Then the very next day Peeko laid an egg. It has been 4 days and no more eggs have been laid. It was laid in her cage. We called the breeder all panicked and she said to put it in a bowl with ripped paper in his cage. Since then Peeko has been sitting near Petey’s food/water dish. She has not been sitting on the egg. She does not seem distressed. She is just mean! If we go in the sunroom our once sweet bird is hissing at us. Then Petey swoops down towards us. It is like they don’t want us in the room. Also, they have become EXTREMELY loud. Of course Quaker’s are usually loud but this is borderline unbearable. We don’t know what to do. We don’t like the behavior change. We heard if we remove the egg she might lay another one. Should we just separate them in two different parts of the house? One upstairs and one downstairs? Please help... hard to believe that our birds could change this much in one week. Is this behavior permanent? We are at our wits end. Just can’t believe this happened after they have co existed for 9 years together.