Empty nester

Why I'm I here..I mean what I'm I doing..why can't I find my voice. I'm 40yrs old and I feel so lost..my two youngest boys who are 19 and 18 have booth graduated and are enrolled in college. Time has gone by way to fast I feel the last 3 years have been a blur. I'm still butting heads with my youngest who's 18. I feel he's still a kid and my husband tells me it's time to let go and let him make his own mistakes and let him learn the hard way. But as a mother who's been there I just want to guide him to the right path but maybe I do need to let go. But I can't at least not all the way yet. Is this what empty nesting feels like or is this just my 40's crashing down on me. I need to figure out who I am now. My life has always revolved in helping others especially my boys. I just need time away to  think clearly and put life into prospective.