I am so sorry Foxy. You are in the midst of one of those very painful life events. I am remembering a quote that a lot of people agree is a great truth that you have probably heard of. But it is coming to my mind so strongly in this situation you describe, and I think it is real wisdom. Here it is as my mind remembers it:
"If you love someone very very much let him go free. If he comes back, he is yours, if he does not he never was."
Furthermore, if he is yours in the end, you can drive him away for good by pursuing him when he has walked away, and also you can peek his interest and pursuit by accepting his choice, saying, almost shrugging, 'Well I am sorry you are leaving, because I care for you very much, and I believe in who we are together. But if you want to leave, I respect that. I don't want to hold you back. Go ahead. I wish you well."
I could tell you stories from my past experience with SLIs but I am giving you the short bottom line. As hard as the above letting go is to do, it is the only thing that can work.
If you want to know convincingly how/why letting him go is important, and why also acting almost disinterested, or at least totally accepting of him leaving, and why it's imperative to do everything in the opposite direction of being desperate to get him back (which will make him really run), you can read about exactly why that is the strategy. It will booster your confidence in implementing that plan if you read this bestseller,
Love Must Be Tough, which has been many times reprinted, which I just now found cheapest used on Abebooks for
$3.70 with
free shipping:
https://www.abebooks.com/servlet/Sea...20dobson&sts=t