You don't need to obtain a visa.
However you need to leave Thailand border bounce and reenter visa exempt.
After entry obtain a non O retirement and subsequent extensions.
Not having to leave Thailand would have been an option if on good terms with wife and could change your extension to one based on retirement.
Seems not possible.
Obviously non O and extension has more difficult financial requirements.
If you cannot meet these you could consider use of agent.
Edit: after thought..You could pay the wife to attend immigration for the change of extension to based on retirement.