Hi Kinma. My job looks very similar.
What I did was buy a $1 nipple (funny name but that is that the Hardware guy called it). It is a pipe with threads on both ends. You simply unscrew the Pex pipe from the water filter module and replace it with this nipple pipe. Then just screw the Pex ends on to the pipe and your done. I bought a 3" nipple pipe I think. The joy is that the way it is plumbed, your allowed to flex the pipe back and forth to accommodate different lengths of replacement pipe. Only took a few mins.
2006 HW256 (previous pup)
2013 Chevy Tahoe
Equalizer WDH 1000#