"My theory: I had inappropriate thoughts about the female servers at this restaurant because my W was involved in a sexual situation at the same time."
No it's because you haven't had sex in a few months. It's a base human desire and it's nothing to be ashamed of. You're a guy, they are attractive women. Period.
"Sometimes I feel depressed, when there is no real reason for it. "
Of course there's a reason for you to be depressed. Rather than being with the woman you love with your son, you're alone. We all get that way. Believing in God and knowing He's with you is great. But it doesn't compare with having a flesh and blood spouse with you to physically hold your hand and comfort you.
That's why it's not easy.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.