22 years ago and he is searching for me, I'm a birthmom

RonneyKay, I'm really excited for you. He's definitely your son, and he's a sibling to your other children. HOWEVER, you're right to be cautious when using those words with him. He may or may not think of you as his mother. He may or may not think of your children as his siblings. I am an adoptee, so I cannot give any advice to you about telling your other children. But, I am thrilled that you are planning to let them know. I hope that everything goes well for you.