Rear break hose on my 2006 e91 doesnt fit the breakpipe after removal

Hello, my 2006 325i right rear brake was constantly breaking, even after i tried changing breakpads and cleaning the old caliper. So yesterday i was going to change the caliper and breakhose and it was all going well except for then i was trying to screw the new brakehose onto the pipe it at first semmed to fit but when it got like halfway screwed in it just went round and round (i used my hands so it was no excessive force) and so i tried to push them together at the same time as i was screwing and i felt it was grabbing onto something but then just let go and just went around again, and when i was screwing it of i felt that i could wiggle it quite a bit when it was still a bit screwed on. And so i thaught i must have bought the wrong hose and i tried screwing the old hose in again, but now its the exact same thing on the old one!! I also tried screwing in the old hoses outer thread (that goes into the caliper) into the new hoses inner thread (that goes onto the pipe) and it fits perfectly! I did vice versa as well so im thinking that maybe i in some way damaged the breakpipe threads? Although i dont see any damage except some rust, but i sprayed it with rust remover and brushed it with a steel brush and it did nothing. Has anyone had this problem before? Or does anyone know any useful info? I will provide with pictures as soon as i get back to the garage later today.