Have you concidered personal counselling to help you through this Bootneck1? Your doctor should be able to refere you or, if you go private then check out therapists in your area via the BACP website.
You are going through a bereavment, a loss of the dreams that you had with your wife. Look up the stages of bereavment, it may help you to understand your feelings, the process you are now in and empower you.
Be kind to yourself, eat well.... Lots of veg. Drink lots of water.... Dehyration headaches on top of stress is an unpleasent combo. Exercise.... Get out everyday, with your son too when he is with you, go for a walk then pop into a park to play with him. Try to go to green spaces, being out in nature is therapeutic.
Have a regular bedtime schedule and routine, if you can not sleep just resting in a darkened room whilst reading a book or meditating is better than nothing.
Valerian Root tea before bed time can help as it is a calmative herb. Scull Cap for anxiety, St Johns Wort if you are feeling mild to moderate depression (use sunblock, as it can make your skin photosensative). However if you do take any herbs you must check to make sure that they dont interfere of have adverse reactions with any other medication. Always make yourself aware of possible side effects. If you are on any perscription meds you will need to tell your doctor.
If you have a supportive family and friends talk to them, ask for help, let them be there for you.
Last of all, keep your emotions regarding your break up away from your son. He will have his own difficulties with everything going on and you need to support him.
I am so sorry that you are going through this, but hold your head up high, dont play games and give yourself time to adjust, grieve and heal.
You can only control your thoughts and actions, you can not control hers. Act with dignity and hold your head up high, you will get through this, you have to for your son.