This will not improve overnight. Things are so out of hand you need some assistance with behavior management. It's best to arrange an appointment with a behavioral specialist and you can contact your insurance company to locate the appropriate provider.
do you think that it would help to get him in with a behavioral specialist? how long do you think it will take to get it back in control?
Yes, I do think that would be useful. But remember: he will change to the extent that you can make some changes.
If you find that the therapists in your area have a long waiting list, and they often do, contact the local school district's counseling department for possible resources. Many districts contract with a public health provider who might be able to help him sooner. If there is a college close by, check them out to see if they have a counseling department that provides play therapy. Be sure to take care of yourself when you feel frustrated with him. I remember how tired pregnancy can make you feel and with him pushing your buttons, it has got to be stressful. Ask for some help to give you a break.
Sorry about the situation you are having with your son. From my own experience, I was a nanny to a child with very similar issues. His parent's chose not to discipline him or did so in a manner in which the child did not understand that his actions were inappropriate (they also were not present in his life and he felt a lack of love on their behalf and acted out because of this). I agree with the comments above if you feel the situation is beyond your control as a parent I would seek a therapist. Monitor the people with whom your child associates they may be a bad influence also TV teaches children a lot more than they should know consider adding parental controls to certain channels you do not want him to access. I hope the situation improves. Looking for help shows you love your child. Take care and God bless.