I think the holidays are depressing for a lot of us. Maybe your husband returned quickly to spend time with the woman he's dating....who knows.
I saw a functional medicine practitioner today who knows about my husband and she believes my husband feels guilt. I don't think he does, but she said his hostility is a sign of guilt. Perhaps your husband avoiding you is a way of avoiding dealing with his guilt as well.
It's easy to be depressed when you reach the point where you give up on saving the marriage. Up until this point there's always some hope or something else you can try. Once you believe in your heart that the marriage is done it's like grieving someone who died. It's so hard.
I'm depressed and one of my friends who has been especially caring started sending me messages non-stop about positivity. We do need to be positive and for myself I do believe in a year I'll likely be in a better place than now, but right now the pain runs too deep to just think happy thoughts and the problem is fixed. I'm sure you feel that way too. It's good your kids are supporting you. Do they know everything that's going on?
I hope now that the holidays are over and everyone is back to their normal routine it'll be easier to function.
It's easy to feel isolated in times like these. There must be a separated and divorced support group in your area somewhere. I keep trying to find an active one in my city but haven't found one yet. I don't even know how I'll make it to one with my daughter to care for but I'd like to find one.
I hope this part of your life passes quickly. Perhaps you'll meet a new man someday and will want to perfect yourself as much as possible in the meantime to be ready for a happy new relationship where you're treated like a queen with lots of love and affection!