I'm sorry you are in so much pain Carlos. The pain will pass, although sometimes it may feel like it will kill you first. Keep breathing and cry the tears you need to.
Have you heard of "anticipatory grief"? I usually hear it in the context of terminal illness of a loved one, but I think it applies to any impending loss. Anticipatory grief is when you worry about and grieve over losing someone you love before they have actually gone. Sometimes you worry so much about what is around the corner, and how you will cope, that you forget to enjoy the time you have together now. You may begin to focus more on your son's impending absence and the pain you will feel when he leaves, than on the fact that right now, he is still with you. It is normal to feel that way, but the danger is that you may sub-consciously try to distance yourself emotionally from the person who is leaving in an effort to spare yourself pain when he leaves, but you are going to feel pain at that time anyway so you may as well savor every moment you have.
You have had an incredibly difficult year. Undoubtedly you, like everyone else on the planet, regret some of your choices. All you can do is your best right now and moving forward. Difficult as it has been, it looks to me like you have made some very good choices in this past year.
Hang in there Carlos. I'm glad you are reaching out. That's a very healthy thing to do.
