Solanum crispum 'Glasnevin' pruning

I have a Solanum crispum 'Glasnevin' that has been growing over a metal arch for about 4-5 years.
It has become a bit top heavy and as I will be replacing the arch fairly soon I thought I would cut it back a bit.A couple of the main trunks have become entwined in the arch frame so will need to come out.
It is already beginning to shoot and I have trimmed back some straggly branches but how far can I safely cut it back.
Here it is last May:-
“Every day is ordinary, until it isn't.” - Bernard Cornwell-Death of Kings
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I used to look after a garden which has one of these. It made me decide I'd never plant one in my own garden.
It was a beast, marched its way up the wall and had to be regularly pulled out from the attic space. I could throw out shoots 3m long in one season.
Passion flower is another one which is being removed from my garden this year.
I have a couple of them and they're just thugs. I'm sure there are gentler, prettier varieties, but those in my garden are brutes.
I may have broken the rules, my Solanum crispum 'Glasnevin' is 4 or 5 years old, very strong every season, but this summer has been heavily encroaching on my neighbour, I have cut back about 10% of the growth (in July), and intended to aim branches away from the neighbour, but it seems to have reacted badly . The flowers and leaves all appear to be dying. Will it recover ? maybe next year ? or have I murdered it ? Its a great climber and I would like to save it. Thanks for any help