Portia, How are you doing? I know you've got a lot on your plate right now and you need to take care of yourself.
Sounds to me like it looks to you to be his lifeline when things aren't going as well as expected. I don't think he's as happy as he makes himself out to be. If he were, he wouldn't be contacting you like he has been.
I would continue to do what you've been doing, i.e., little contact. I know you love him, but he's w/someone else right now and he only calls you when he's possibly alone and the ow isn't around. That's having his cake and eating it too. He's stringing you along in case the current relationship doesn't pan out. Friends don't usually panic when they can't reach you. They generally call or text and leave a message and wait for you to respond back. This guy is very insecure and I wonder if he's got abandonment issues as well.
You can have compassion for him, but don't allow that compassion to suck you dry and down into the rabbit hole w/him. You are a wonderful person and deserve so much more than what you are getting from this guy. I have a feeling that if you were to tell him to bug off, he would be even worse than he is now in contacting you. He's very selfish and self absorbed and doesn't realize what he's doing to you emotionally. Only you will know when you've had enough...but I would definitely go dimmer and allow him to wallow in his own stew for a while. After all, he's got the ow that can take care of him and listen to his woes.
Portia, please take care of yourself. I do hope your family is doing okay.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
