The problem is that as long as you stand for his nonsense, he'll come continue dish it out. It's a power thing with him and he wants to retain all the control.
23 years is a long time. I don't think that should be ignored, however, I also think you have every right to and should express what he needs to do for you to be happy in the marriage.
You have a voice so let it be heard loud and clear. I think you're doing well in terms of getting on with your daily life without him. He's not seeing what he saw last time and he's wondering where your stength is coming from.
Keep it up, as it empowers you and helps make you look strong. You won't go back to the you who was suicidal this time - hold it together and exude confidence.
You know a friend of mine got dumped a while ago by text. She replied saying "Ok, good luck" and he (the dumper) was furious. He started saying she obviously never loved him with that response and he was going to propose, but he's glad he didn't.
She just said - no worries have a nice life. A few days later he was texting profusely trying to get back with her.
The less you care (or the less you show you care), the stronger you appear.
It's not just a case of him saying let's try. What is the root cause of him wanting a seperation?