The lack of emotion you described is called anhedonia, I personally feel it follows as
a numbing effect after years of hypersensitivity to emotion you've suppressed and is a coping strategy that can then spiral dangerously downwards as lack of feeling sucks all the meaning out of life.
Suicide is never an option for reasons way beyond the scope of this reply as the implications are immense and exceedingly real. Not just for yourself. Congratulate yourself on doing the right thing and calling before checking out,
3AM is a dangerous time to be awake and its quite frequent on The Coli:
By regularly I mean at least a 2 out of 7 days. If so click the poll with what times this is please. Poll is anonymous and unlimited as people often rise twice in my experience. Also this isn't your usual kind of getting up after a nights sleep, it can be described as "One moment you're asleep...
www.thecoli.com
Your issue, as I intuit, is unexpressed anger and a deep seated rage as well as sadness/grief you haven't allowed yourself to fully feel. Learn how to box, its very liberating once you've been punched in the face and handed out a two piece in return plus it generates a totally different kind of more sustainable euphoria when you're facing off against someone in the ring. Excellent healthy release.
Also, when you're out
driving in your car scream, yell and just let whats inside out. Grab a red pen and notepad - write down what you feel because then it is "outside" and offers a far more objective perspective as well as release from carrying the tension.
Taking a walk in the forest, along a beach and uphill and imagining you are
breathing out your tension as a dark smoke with each forceful exhalation (longer outbreath than in) can induce euphoria quite quickly as well due to the synergy and natural assistance of the environment which helps with finding equilibrium.
Once you start doing these things as a method of lessening the burden of a life of not expressing your authentic emotions you'll see the real start to poke through and thats when the real fun begins. What you experienced is perfectly regular and should be prized as its
the start of a realization that you've been living a masked existence and are now just awakening to the reality of the garbage within which has accumulated over time and must be dealt with.
@Doobie Doos idea of a bowel cleanse may have been in jest but there is a lot of truth in that as the intestines "hold on" to unprocessed emotion so that can help a lot but in your case I feel its definitely anger and that usually prefers a more direct vent so find something constructively destructive.