This is the channel switching of narcissistic people I mentioned earlier. The channels are:
(1) self-pity/guilting
“it’s stupid how heartbroken I feel bc you never loved me that way”
"your son doesn’t want me to leave"
"long messages about his autism"
“I gave you everything. Please don’t ever tell me you loved me again”
“Tell yourself that I’m the one walking away if it makes you feel better”
(2) blaming/insults/punishment/rage
“I’m not against something casual on the side in an open relationship but it’s not reasonable to ask for that as an exclusive relationship.”
"Lots of tears about how I betrayed him, lied, only care about money."
"don’t punish me for being autistic"
"how if the shoe was on the other foot and he was the one with more money/house and I was chasing to speak, he would be the one in the wrong"
"I’m the one who DGAF"
(3) charm/love bombing
"there has been a flurry of messages, love bomb-y in nature "
"he’ll give me time but ultimately wants us to get married and all be a family"
People like this switch between the channels to see what works to get them a response. If there is no response, they'll switch between the channels faster and faster, trying to confuse and provoke the victim into a response, any response.
Any response - including angry - is a win for them.
Responding after they send XX texts also just shows them that XX texts gets them a response.
I understand that at this stage, it's helpful to read what he's sending, since he's just digging his grave deeper and consolidating your suspicions. At this stage, it's a healthy part of breaking up and healing.
But be careful not to let this go too far or too long, because it'll keep you bonded to him and unable to move on. It's also very exhausting and draining, and time-consuming. You sound like a very sensible person, though, I'm sure you'll recognise when it's time to block him.