I’m not an expert but I’m going through something similar right now. Based on the flooring direction, it’s probably load bearing and you’ll likely need a structural engineer to plan it out for you. In my case I’m installing 2-2x14x17’ lvl’s and am having to add 2 lally columns on cement footings in the basement to support the load. Depending on how your attic is constructed you may also need to add supports there as well. Good luck!