If a JW knows a JW lawyer, or asks around for one, then sure he could have one. JW lawyers don't work exclusively for the Borg, except for the ones that work at the branch itself. For example, the attorney for the defendants in the Menlo Park, CA Kingdom Hall/elders case is a JW lawyer but he doesn't only work for the Watchtower. I mean, the Borg is busy legally speaking but not THAT busy. The JW lawyers have their own practice or work for other firms, too.
So if your ex-husband is in a relatively decent sized city he is likely to be able to find a JW lawyer if he wants one.
Do you have a copy of the Watchtower's "child custody packet" they give to elders and JW lawyers to help them tell JWs and their kids what to say in court? Your attorney will need it. Many of us here can send you a copy.