I did the worse thing ever by filming interlaced. They should remove that option from cameras.
No don't remove it. In PAL land shooting anything with sideways fast or close motion is much better with 50i than 25p as the latter can be jerky. Of course if your camera shoots 50p then use it as it should give better quality than 50i. I've never had any problems shooting 50i but then I always deinterlace with "Interpolate Fields" to create 50 frames. Blending Fields just results in blurred jerky motion.