Fear of being alone after kids leave the nest

Am 42 and have 2 children, 18M and 16F. Have raised both away from my home country in the UAE but am originally African. My first has already left home and is now in Uni and my second is following either this year or early next year. My husband and I are planning on returning back to our home country in a few years. However, i find myself getting so scared of restarting life with just the two of us. He is not keen on having another child, he turns 50 this year by the way. I honestly was willing to risk it but am also scared of complications and risks which come with such late pregnancy. Have thought about adoption and fostering but its not a popular practice where I am from. I feel like after my kids leave i will be all alone with no purpose in life. I am currently working but absolutely hate the job i do and cannot wait to leave.

Are there any in my similar situation?