I'm truly sorry you are here. We know how you're feeling and what you're going thru.
Others will be here shortly to help you thru this.
The first thing that struck me from your post is the possibility of infidelity. The PI will hopefully sort that out for you.
Be careful about letting her dictate terms to you. It sounds like you're a nice guy and willing to please. I know how scared you are of doing anything to push her away.
The advice here is that you do not leave the marital home. If she wants out, let her find her own place. Fight for rights to your child if she decides to leave.
Be strong, confident, firm, positive and lovingly detached. Don't panic. The calvary will soon be here.
