From my limited experience it sounds a lot like grief that you are expressing. That's completely healthy and grief comes in stages especially when the outcome isn't what we expected such as .. the sig other moving on before we do .. and he's a man .. usually men do quickly as they have a harder time being alone .. you mentioned he was 70 .. well I'm sure he needs a nurse at this point.
Has he changed .. no not really .. maybe for a year or two .. not forever. The old behavior will come out with the new wears off.
I'm very sorry for your pain and confusion.
You might be right .. maybe the two of you weren't right for each other .. I tend to believe in my naivety that leopards don't change their spots over night. I love how people jump from one relationship to another as if that is the magic fix .. doing the work on the inside leads to a far more fulfilling life. Have you considered going to divorce support or counseling?
I really encourage anyone to live their life to the fullest and find YOUR passion and what you feel good about.
I watched my STBX's s/mom go through a divorce after almost 34 years with his dad .. she was roughly your age I believe .. she was angry how fast he moved on and how he got remarried literally within 2 years (or less) of their divorce being finalized. She was not happy in that marriage .. like father like son .. there was abuse, infidelity, addictions, I remember her being so devastated even 5 years into it. I was so sad for her because she stopped living her life and was so focused on HIM, did he ever think about HER .. did he ever ask about HER .. he's never called his grandchildren at my house going on 5 years .. I think he's spoken to the kids 2x maybe 4x in the past 2 1/2 years. Personally I'm glad they don't have a relationship with him .. he's a sick guy. It's where my STBX is headed.
My point being .. you have a right to be happy .. I think I loose focus when I falsely believe that someone's outside package somehow looks better than what I know to be true on the inside makes the outside package more true and that's a false belief. That doesn't mean I need to be bitter .. it just means .. I need to remember there was a reason we got divorced and if he wasn't good to you or for you .. be glad you won't be the one who will be taking care of him when he's sick. You deserve better.
It sounds like you need an extended NO INFORMATION time with regards to ANYTHING about your ex. Whatever/whoever your source is, tell them to stop. You not only don't want to hear it, you can't. Because it's making you ill. You don't need to compare, you don't need to dive into the whys, you don't need the grief.
It's time once again to stop yourself each and every time your brain turns to thinking about him. Say it out loud if needed, immediately turn your thoughts to something else, shake him out of your head.
Now if the $ he is spending needs to come to the attention of your attorney....that's another matter.
Sounds to me that he's going through his 'bucket list' really, really fast. From what you are saying,... maybe he's panicing at '70'. The "I wants", and "must have's" before it's gone. The face and body look 50, but inside, he's 70 and he knows it! I say, 'look the other way and enjoy your life' ! ! !