@chenml60 How old/heavy is your baby now? I would say maybe revisit the sleep sack situation and see if that helps. Babies change all the time so it could be he'll be a little more malleable now than he was last time.
If it were me, I'd probably put him into a magic Merlin sleep sack (it makes them look like the stay puft marshmallow man but has a very soothing full body hug type thing happening and it modulates their startle reflex. I'd let him fall asleep next to me and then slide him over to his sidecar bassinet. I'd also us an electric heating pad that I could place between the two of us so that baby could feel warmth if he snuggled nearer to the side where I am but not actually be able to get his face against it.
All that said, I realize that might not be possible but I'd probably do some combo of trying a sleep aid (if not the Merlin, the zipadee zip is another good one if they are rolling and cannot be swaddled, otherwise the Ollie is good if not) and being near to them and using a heat source to "soften" the transition.
Another option is the guava lotus travel crib. It opens from the side so you could sleep on the floor on a floor pad and do the same thing but slide him into the travel crib and zip it up after he's slid so as to separate the two spaces.
Just trying to brainstorm in case you're looking for something else outside of cosleeping. Hope you get some good sleep soon!