Hi OP,
It sounds like you are really struggling. However, it also sounds like you are stuck in a place where you dont believe things will get better with the life you currently have, as opposed to a (fantasy) life where you suddenly have hot sex and amazing romance with a new man. Just recognize that the desire for the latter is a symptom, rather than an answer.
Given that you didn't list any red flags in your relationship with your DH (addiction, abuse, adultery) it sounds more like you are unhappy, internally, and have given up on connecting with him. He may feel the same way. Its okay--you are both different people than when you got married, but there is a good chance that you can fall in love wiht each other again. You will need to do some internalwork, first, though, to address your depression and find some sources of inner happiness that have nothing to do with your marriage. I suggest a primary care screening for depression, hormones, etc, and then find a counselor. You need to get your groove back.
I would also , when you're ready, try to engage your husband on how he feels about thigns and what he wants. RElationships can go through funks, and seasons. Depression can make it seem like it will never change or get better but it absolutely can.
Also, I kind of find that mid 40s suck--you're still rearing kids, wondering if your career will hit a stride or not, what have you achieved, etc. I am on the other side of 45 and have been thinking about this article:
https://www.theguardian.com/society/2018/jul/21/midlife-crisis-myth-life-gets-better-after-50