Is it water under the bridge between us now we have two kids and I have known him 12 years?

My ex just lost his dad Friday we have a near 6 year old with autism and a daughter 3. He was very hurtful to both my kids and I when we were married and we separated after 2019. I have divorced 3 years ago and since been with another man had one more baby and I am single again as he wouldn't leave his wife. My ex ever since we separated in 2019 has been my friend, going out some times as a family. I was the first person he texted 7.30 in the morning after his dad died. But I am just seeing if it is my vulnerability after my recent split causing me to feel down or because my old father in law is gone and we have history with that side of the family, but I see my ex slowly returning or showing change and reaching out to me more. He had his licence suspended for phone use and I had to hand it in to the Authorities, he has asked to feed our old dog at his house while he has gone and gave me a key. (He took a plane Monday night at midnight with the funeral being Thursday and left for one month now) but at 6.00pm before he came to see my kids at home first and left some desserts, my first son turned on his water works, his sister did then I could feel myself welling up. He wrapped us in a hug. The first time I stopped my ex from leaving we did partner visa and married we didn't work out and had to separate as we fought a lot. Is it really now water under a bridge as I have known him 12 years and we have our 2 kids? Is he just taking advantage more that I am single or has nothing really changed and we still pine for each other because of our kids. Could he be seeing me responsible now our two kids have grown, my son is just months from starting school. With him not driving 6 months I will find myself doing a drop and pick up of kids. Has anyone ever been back to someone before and did it work? By the way, maybe now also he sees me getting to.be financially stable as I manage all my budget and cook, I.do have a job interview on Thursday next week, he now is a citizen.