I'd say your wife has gone way too fast - three other partners in 6 months when you're so new to the whole idea!!!! It's taken me two years to even accept that my partner is not going to get over it; that I can't make him monogamous by beinthe most awesome partner on the planet; or that I actually want to stay in the relationship if poly is the way it has to be.
Having said that I do understand how women can go a bit crazy after a long period of time in a relationship where they have struggled internally. If she was poly and living a monogamous life with you not suspecting anything was wrong she was probably struggling very hard to cope.
Don't be afraid to communicate your feelings and negotiate a way forward that works for both of you. For polyamory to work you both have to be happy.
It does get easier.