May you sue the opponent’s attorney?  A quick look at the principal of privity says: "No."  Here is a rare circumstance when you may sue the opponent’s attorney.  This particular husband failed; the opening remains, however.

Mars v Grant
2007 NY Slip Op 00576
Decided on January 30, 2007
Appellate Division, First Department

"Plaintiff, who is also the plaintiff in a divorce matter in which his wife is represented by defendants herein, failed to support his pleading of a cause of action under Judiciary Law
§ 487 with allegations that adverse court rulings in the matrimonial action were based on acts of deceit by defendant attorneys (see Melnitzky v Owen, 19 AD3d 201 [2005]), or allegations pleading the required elements of fraud (see Manna Fuel Oil Corp. v Ades, 14 AD3d 666 [2005]), including detrimental reliance (see New York City Tr. Auth. v Morris J. Eisen, P.C., 276 AD2d 78, 86 [2000]). The failure to plead detrimental reliance is also fatal to plaintiff’s cause of action for notary liability under Executive Law § 135 (Rastelli v Gassman, 231 AD2d 507, 508 [1996]), which, in any event, is pleaded in conclusory terms without any specificity. "