Am I obligated to reveal joint tax returns on a civil suit which I am the plaintiff?

Talk to your lawyer, but assuming that your personal injury arises from either a MVA or a premise's liability claim, and assuming the defense has not moved for non-standard discovery, under CT's standard discovery you are only obligated to produce "that part of all income tax returns relating to lost income filed by the Plaintiff for a period of three (3) years prior to the date of the incident and for all years subsequent to the date of the incident through the time of trial". While we routinely produce complete tax returns for expediency, if there is a concern, you could ask your lawyer to redact all information related to your wife and that does not pertain to your lost income claim. Ultimately, however, your lawyer will know best and you should follow his/her advice. There may be a tactical or other reason to produce the complete returns.

Your lawyer knows more about your case than anyone else and can inform you about the status and reasons, i.e. whether it was requested in discovery, whether a judge compelled production, etc.

Generally speaking, you should not have to disclose your tax returns. However, you might have to do so if the other side has obtained a court order compelling the disclosure. It is best to address this question to your own attorney.

You really need to run this question by your counsel. Having worked as an insurance defense attorney in the past, sometimes I procured tax returns to demonstrate a financial motive behind injury claims.
Good luck!