I know it's completely normal to be this overwhelmed at first, especially since I've only been a 2u2 mom for a week, but I still cry daily over me not being able to spend all of my time with DS1 anymore. I feel like I barely see him because I'm pumping and i'm always attached to the pump and when I'm not doing that, i'm either changing diapers or feeding DS2. It's killing me. I love DS2 so much already so please don't get the impression I don't, but I just am beyond upset I can't just pick up and go with DS1 and do fun things with him anymore.
Re: beyond emotional
I struggled with the same issue. My solution was to sign DS1 up for 2 weekly classes and have someone come over and watch DS2 while I went and just spent 1 on 1 time with DS1. It was just 2-3 hours a week, but it really made a huge difference for me and, I think, made the transition easy for DS1. If there's a way you can manage something similar, I high recommend it. Also, this is truly much harder for you than it is for your DS1, so don't worry too much about it.
Hang in there... it gets better. And, congrats on your new baby!