A Sydney mother is raising alarms about a man who took advantage of her vulnerability when she was newly single. Last year, following the end of her 11-year marriage, Jaixi “Sissi” Wang met who she thought would be her perfect match through the dating app Bumble. “He was in finance, six-two, without blue eyes but he has a trust fund — and he has two children,” Wang said in a viral video recounting her ordeal. A newly single mother believed she h…