Great story! And hopefully an awesome sober....FRIEND.
It jumped out at me that you said sponsor each other. That's not how it works- and you guys are in very different places. I'd strongly suggest against jumping into a situation where y'all think you can sponsor each other....he's coming off a relapse and has previous time and experience to share....but he needs some stuff now that is different than what you need as a some with 293 days.....also - around here, usually a yr of sobriety is the marker for doing so. Even if it's not where you are, it's a pretty good idea to give yourself that time. And, he shouldn't be sponsoring anyone, the way the program is laid out here in terms of sponsorship.
If I've missed some posts by you, WDP, forgive me if I'm off a bit here- but the co-sponsor thing isn't a good idea (and I'm not sure how it would even work, really). If you are already working with a sponsor and moving along thru the steps, then this sounds like an awesome opportunity to learn from someone and vice versa and help each other as sober friends.