Bethenny Frankel hasn’t always enjoyed celebrating her birthday. The 54-year-old star shared her birthday with her mom Bernadette – who died of lung cancer in April – and Bethenny has now admitted that their “complicated” relationship made it difficult for her to celebrate the occasion. The TV star wrote on Instagram: “I was born on my mother’s 20th birthday. I was never public about sharing her birthday. Our relationship was complicated at best and it represented pain and shame. Its symbolism was inescapable. “Birthdays have always been an incredible source of anxiety. Like Goldilocks, too li…