Spaticles

So my girlfriend's xA threw a knock sensor error. I dove in there and found this little problem here. The cable from the knock sensor TO this harness is OK. However, from the harness to the power source, you can see that the white wire is cut right at the harness, and of course, the white and black wires come together into one of those plastic ribbed harnesses that hold a wire bunch, like in the bottom of the image, so I can't just replace that one section. My question is, does anyone have any good idea as to how to fix this? There's literally like 2 mm of white wire sticking out of the harness, so I can't just splice a piece in there. Could I maybe pull the white wire strand out of the rubber harnesses thing and try to slide the existing wire in there, or splice a new piece to the existing, and slide that one into the harness? I feel like that won't make any kind of a good connection.

Spaticles

Ok, so I got the wire out of the harness but I broke the wire holder when trying to uncrimp it. So, any idea where I can buy that single gray harness?