Will you help me understand my feelings on marriage?

I feel badly about feeling like this and don’t know if it is normal or not. One of my sons got engaged and I wasn’t happy like I should have been and they both sensed it and I just told them I was so overwhelmed. Actually I did not like it but I didn’t want to admit that to myself. I actually like the girl he is in love with. Now that the actual wedding is only months away just thinking about my son getting married and what i call “losing him” is almost giving me panic attacks. We are very close and I do not want to give up that closeness even though he is at an age where he probably needs to get married. I sometimes wish they would break up but then I am in my early 60s and I should want him to have a spouse and children. My other son will be getting engaged next year. I guess I put too much of my life into my children and don’t want to give them up. How can I get over this and move on?