Christmas stuff and how much I hate clutter

Well, I don't really have much of a family and I am used to spending the holidays alone. I kind of like it actually. Until very recently I always found some friend who needed dog sitting and spent a few quite days alone while the rest of the world was going crazy. Well, this year I kind of had to go crazy with the world. I spent Christmas with my girlfriend's family. They were very nice, let me bring some of my animals along (now I have my own animals and I have discovered how impossible it is to find a dog sitter over the holidays) and made sure there was vegetarian food for me. I ate too much, mostly crap,  and spend a total of 12 hours driving in the span of 60 hours. However when I finally got home I did go to the gym (I was practically the only person there on Christmas day) and ran my scheduled 3 miles.

Now the question is what do I do with the stuff I got. I am kind of a minimalist and I hate getting stuff as presents. It is never really stuff I need but I feel guilty giving it away. For example I got a set of closet organizer bags. The set is huge because the bags are really good quality with fabric reinforcement. That is all great but I keep my closet about 60% full and through away everything else. This thing comes with a show storage thing for 18 pairs of shoes! I currently own a total of 7 pairs of shoes and of those 4 just need to get thrown away the next time I go through my closet. There are also under-the-bed bags. I hate putting stuff under my bed. If I am storing it under the bed that just means I don't really need it. Plus my cats like to sleep there. My girlfriend and I also got a set of 8 glasses. We already have way too many glasses, mainly presents for my girlfriend from her family.  I have a really hard time convincing my  girlfriend to throw away stuff. The result is that we have a ``storage" room where I am not allowed to enter (and one really cannot enter it) full of stuff we don't need. When I am surrounded by stuff I just feel stressed out all the time. I need space not stuff! So I don't know what to do because it is her family so I don't want to be rude. Any ideas?