Wow! So sorry about this, eelouisa! No doubt, a colicky baby can cause a lot of sleep deprivation, stress, and anxiety for parents. And I suppose it can drive a wedge between them. One of my DGC suffered from colic and I know how difficult that was for DD and SIL. Fortunately, they were able to learn to pull together in the face of this problem, but unfortunately, you and DH were not. I don't mean to sound as if I'm blaming the baby. I'm not. It's the parents' relationship, IMO, and how they handle issues that causes a rift (or not).
And, sad to say, it certainly sounds as if your marriage has gone sour and was going that way before baby arrived. In fact, it sounds as if the boy you probably adored when you were 16 has turned into a man you don't care so much for. And clearly, he has his gripes about you, as well.
I suggest going to Relate. They may be able to help you get your marriage back on track. If not, then, IMO, you'll have to be prepared to seek divorce. It's so loving of you to be concerned about DS (dear son) needing his dad, but his dad will still be part of his life, especially if he has liberal visitation. Best of luck!