I am not sure if you would be able to make poly work for you right now while you are struggling with insomnia and a lot of mental stress plus your career and wanting to date other women. Poly would add even more stress on top of that, most likely without the benefits your are hoping for since it is more difficult for partnered men to make poly work for them than it is for women. Prioritize getting help for your insomnia. Seek individual therapy if you can, and start dating as a single man. In the meantime you can read up on polyamory and work on your mixed feelings surrounding womens' right to own their sexuality, and perhaps in a few years you will be able to make a poly relationship work for both of you.