What a horrible experience! I'm really sorry to hear you were put through that, Laura, and I hope your nerves and blood pressure have recovered!
I understand the ticket guy not wanting to be a hero, but surely he should have (a) shown compassion and made sure you were okay and (b) contacted the office across the tracks to immediately arrange for the CCTV recording to be relayed to British Transport Police. This was certainly, as someone said here, an assault, even without the chewing gum - not just a common or garden fare dodge.
Obviously not at all in the same league - but you remind me that I was astonished the other day to see someone exit The Glades shopping centre car park in Bromley by tailgating right after someone who had paid, nipping through before the barrier came down! Unbelievable nerve, some people have.