I'm in an identical situation as you (also from the UK funnily enough), except I did keep in contact with her, albeit at arm's length at first. She's explained to me over the years that it was internalised hatred, made worse by her family's very outspoken views about anyone not straight and white.

When she finally had a chance to get away and start thinking things through herself, she began to accept herself and others. She's a lovely person to be around now, and pretty vocal in trying to help other people learn about and understand trans healthcare and mental support. But most importantly, she's happy.