Brian Austin Green doesn’t know how to “process” the death of Shannen Doherty. The 50-year-old actor starred alongside Shannen – who died on Saturday (13.07.24) at the age of 53 following a long battle with cancer – on the hit series ‘Beverly Hills, 90210 ‘ throughout the 1990s and paid tribute to his former co-star as he thanked her for supporting him throughout the years. He wrote on Instagram: “Shan. My sister… You loved me through everything. You were a big part of my understanding of love. I’ll miss you more than I know how to process right now. Thank you for the gift of you.” Other ‘9021…