Because I don't think we really have enough context to be able to state "Why, she's unhappy with her marriage! That's mania/hypomania of course!"

And tbh, nothing in your post really seems "manic" to me, aside from maybe making the purchase for your child's gift and sacrificing the price it costs to buy school books (i.e. it sounds like an impulsive purchase) but I'm sure your heart was/is in the right place. But I think asking for a divorce and agreeing to wait 6 months to see if things improve sounds reasonable and responsible.

EDIT: Changed "abnormal" to "manic." Also your leg shakes / jitteriness could be due to stress factors.