Sparks, cut yourself some slack - in just a few weeks you had an anniversary, 2 birthdays, and mothers/father's day? It's like the winter holiday season all over again for you, isn't it? Of course you're going to feel really down and tired and sad about all those milestones passing. I think sometimes just getting validation helps and I am telling you here and now, it's ok to feel low. Father's Day (happy father's day!) is tomorrow, I'd look at it as turning a corner. You have an adorable, healthy baby. You're a nice, fun person. Life's going to be good. You just have to get there and enjoy the bumps as best you can.
Is she even still pushing for custody changes at this point? Rushing away at hand off time? Giving you weird vibes? She might be seeing someone or have figured out something she's not ready to tell you. I could be wrong, but either way you need some space and a break. The person she is now won't make you happy - she can't even make herself happy.
My advice is to get plenty of sleep and drink lots of water. Schedule things to do with other people as regularly as you can. Check your local hs or community college for free or cheap classes. Go to stuff like free lowe's/home depot workshops, library story hour w/son, free summer movies and concerts w/friends or fam. Keep the yard and house and car nice/clean so you feel good being in those places. You also need to start. Learning new things - you'll have a toddler in no time. He'll want to know what the bird's names are and what's in that food and what kind of plant/tree/animal that is. you'll be a great dad - you celebrate that tomorrow and get yourself some peace of mind. (And may I suggest a foot massage? Pretty cheap around here and would be super relaxing)
Faith is, at one and the same time, absolutely necessary and altogether impossible. --Stanislaw Lem