Thendral_USA, After Charu left for Britain, we have seen Joseph visiting TA and T as well as APD living with this couple. The director could very well make a twist in which both of these are not the spies because these are the persons whom we could suspect as spies. As far most of the others, TA went to see them. One intriguing question even now is, why J told TA he could arrange money for him, when he was the one who took TA to the loan sharks. What did J mean that way?
It is even possible APD and her husband are putting up a drama and APD could have even told a lie in the temple itself to confuse TA. Charu despite being a psycho has a (crooked) purpose and could have overworked her brain. Somehow she could have been made known to TA's mom also. TA these days believes whether the couples for which Thiruttukalyanams were done live happily.
As another thought, can Prabhakar be the spy? Despite being rich, he likes to take adventurous assignments.
APD's husband could be made related to the rowdy kumbal as another possibility.