You were railroaded by your ex. Betrayed by someone you felt was your best friend and love of your life. She created an image of someone who isn't and never was you. She won.
Now you are letting yourself become the "loser" that she has told the world you are. You are becomming that person to your children as well.
You are making a choice to have her decide who you are.
I do agree that you need to see a doctor as well. You are depressed and need to get moving. If you don't feel as if you can see one today, then don't.
However, just sitting and doing nothing isn't a solution. Get on your bike. Get up and out the door, my friend. You've allowed your emotions to go dormant, but it is time to let them come back out again.
Go for a ride or for a walk. Even if we only do 10 steps to the mailbox and back today, that is an excellent start. We'll just look for 11 tomorrow...and 12 the next day, and so on.
Get up and go outside. Walk or ride. Your choice, but you have to get outside today and start getting yourself back.
Start small, but START TODAY!
You are worth it. We know that here, now it is time for you to refresh your own memory of who you really are.
