Original owner wanting guild back

Want to give some back story here first. The original owner, I'll just call him mike myself and 2 others were CO-GMS when he decided to quit ESO saying he wasn't coming back and the guild is ours and to split everything and do what we want with it. The 2 other gms were power hungry and took 3mil and left when gm was passed to an old fellow officer. Myself and new GM got things running again, put our heart and soul into it. We had no funds left in bank so we used our personal gold to get a trader back etc. 2 months after Mike left he tells me he's coming back and he expects "his" guild back, he's gonna fix everything etc. I'm one to be fair and I have a heart but he's been so erratic with everything and is just taking about making his money back blab blah nothing like hey thanks for keeping it running for me or wanting to help anyone. I don't know what to do and I wanna do the right thing here but IDK what the right thing is. We've held everything together the past two months bc he quit and left everything in shambles. He didn't care when he left so why should we care now? When he could just do it again? Please no nasty comments I just want some advice.