sometimes when i talk to someone i catch myself mid sentence trying to figure out how to finish a sentence because i forgot what was the point i wanted to make. brain fog is real. along with insomnia, weak memory etc. rebooting can get pretty depressing.
maybe MOing with GF is better than alone but i would stay away from it. just cuddle if you cant do nothing else for now.
withdrawal symptoms are peaking in the first weeks so keep going. you may get more and more hopeless until you start feeling better but i see you have a good GF with you so it may be easier than if you was single. stay positive and dont judge yourself for your cognitive impairments. its gonna get better if you stay on course.