Hello and welcome! Glad you are here. I certainly understand your discouragement, as I am sure many here do. However, let me encourage you to think positive... you are off to a good start just by posting here and sharing your "defeated" feelings.
First, don't hesitate to get some counseling for your depression if that is what you need! Also, I would add that eating right and exercising DOES help a LOT toward our emotions and helping us to feel better. It doesn't have to be a lot at first... just get out there and move your butt!

Since you have a son you could even take him out in a stroller or go to a pool and play with him, etc., if it is difficult to find alone time.
Do you have a plan? If not why not give it some thought and get something to get started? There are people here who can help you work on it if you need that. You can always adapt it later if you want but please, please... get started TODAY!
Blessings
Sue