It looks like Kyle Richards and her estranged husband, Mauricio Umansky, are putting on a united front for the holidays. After jetting off to Mexico, the 54-year-old reality star was spotted reuniting with Umansky, 53, in Aspen, Colo., on Saturday, December 23. According to new photos obtained by TMZ, the Real Housewives of Beverly Hills starlet, who wore a red zip-up and a camouflage jacket, and the real estate guru, who sported a green jacket and helmet, looked like she and her hubby were being escorted by a private instructor. As OK! previously reported, the brunette beauty, who shares daug…