Bravo’s upcoming Vanderpump Rules spin-off The Valley has resumed filming in the wake of stars’ Jax Taylor and Brittany Cartwright’s recent separation, RadarOnline.com has learned. The couple first announced their split last week, shortly before The Valley, which had initially wrapped production last year, was set to premiere on March 19. “Many of you guys have been asking me about Jax and I and our relationship,” Cartwright shared on an episode of their joint podcast When Reality Hits last week. “I just think it’s important to be real and honest with you guys because we’ve shared so much of o…