How do I get over my baby boy growing up?

I need advice.. I am experiencing grief and anxiety about my baby boy being all grown up. I still feel the same separation anxiety I had if he was in another room or if I had to leave the house when he was a tiny baby! I don’t know where the years go and I am so happy to see him growing up strong and healthy, but it’s so incredibly gut wrenching that he is now so independent, not needing or wanting me and the idea he will move out and move on. He is my only child and I always wanted 3-5 kids but physically couldn’t because of health issues. He is my whole world and I have poured my love and care and soul into him and it shows. He’s a happy strong well adjusted kid and doing so well. I couldn’t be more proud of him. But I am grieving almost what feels like a loss. A loss of no longer having a baby, a loss of not having a young child to cuddle with anymore, a loss of the biggest part of my heart. All I want is for him to find love and create his own family and be joyful in his life, but it’s also the thought that scares and pains me the most. Has anyone else ever felt this? My husband travels and always has and has never spent much more than a few consecutive days at home since he was born so he doesn’t at all understand. It’s been me and my boy joined at the hip doing life together, every adventure, every walk, every conversation, every dinner time, every morning cup of tea and prayers, every book we read together. I just don’t know how to cope with him moving on and doing just what I hoped he would blossoming into life. Does anyone understand or can you give advice?! 💔