OP, please be more aware that there are so many types of lawyers that have different specialty. Your uncle the lawyer may NOT be the right person to give advice, however, do ask him to recommend a lawyer who is expertise in HK FAMILY LAW and MARITAL laws , which can be advantageous to the mother. Use these advantages.
Err... folks who are judges in HK only know a small area of expertise, but then they would know who are the toughest/best/nastiest lawyers in which area. And yes, you do need to *quietly* get your lawyers in a row before alerting your to-be-ex-husband
You may still choose to file outside of HK, just that knowing the HK laws with input from a good "matrimonial lawyer" in HK is helpful. One of the better lawyers in hk is Hastings & Co, and one of their experts in Matrimonial Litigation is Helen Kong, who gave advice to one of my friends in his case that was filed in Singapore. Did a darned good job.