Swindled by my indian spouse for a visa

Not a positive request for advice, I'm afraid. It would appear that my Indian civil partner to facilitate his entry to the UK and obtaining the two-year spouse visa swindled me. It’s painful for me to accept and I know it just makes the stereotype worse for other genuine guys applying for marriage/partnership visas so please accept my apologies.

I've now been sent a letter from BIA requesting my permission to use my long statement in their decision to issue a "Reasons for Refusal Letter" to my partner who has left me for another guy. The other option they offer is to sign a basic statement to say that the marriage is no longer subsisting. Just trying to understand how chaotic this could all get before I give my permission.

Now, they say in the BIA letter that he could appeal, does anyone know what grounds my partner could appeal under if we both state that the marriage is no longer subsisting, and we do not have plans to live together in the future. If I decide to only sign the basic statement does that give my partner more opportunity to appeal since there are less facts involved?

What is the process for BIA after they receive my permission to use the statement? Do they review the case and how often do they decide not to curtail the partner's visa? Is the “Reasons for Refusal Letterâ€