I am sooo happy to hear that you have such a wonderful family. I certainly didn't grow up in a family like that. Just so you know, in essence, every single mistake we make, no matter how big or small, we will always have to live with because we cannot change the past. You are not even close to being the first person to make a "permanent" mistake and will not be the last to get through it either. On the surface, it sounds to me like you are having serious marriage problems and believe me, I can understand how desperate those problems can be. You may keep all this inside but I can place a pretty fair bet that your husband at least has an inkling of an idea that you are not okay. He seems to be in denial. Sweetie, your husband does NOT have to approve of you being here, or going to a shrink. You are a grown adult and you can make those decisions all on your own. If he isn't okay with you trying to better yourself, then he has a bigger problem than you do. If he loves you, he will support you. It is not to say that it won't take time. He may very well come around. When people cling onto a false idea, it is hard for them to let it go because they find so much comfort in it. If he doesn't come around? Guess what, you had a life before him and you would have a life after him. Noone can live our lives for us, we can only account for ourselves. Let's say the worst happened and you ended up divorcing, you are still a person and you are still a mother, daughter, sister, and probably many other things. Being a wife does not make up who you are entirely. Just so you know, a therapist doesn't just slap a diagnosis on you. They meet with you many, many, times before even suggesting that you have a mental illness. Even then, in this modern world, the only reason a therapist would diagnose you in the first place is for insurance purposes only. Most of them do not work from the perspective that you ARE the mental illness, but rather work with the symptoms you are having. How do I know? I have a PSYC degree myself and have had therapy and given therapy myself. I have seen people a billion times lower than you are feeling right now, completely turning their lives around. I'm not gonna lie, it will not be easy at all. You may have to make some huge changes that not everyone will approve of. But if the people in your life really love you, they will eventually come around. I promise. When you cross these hurdles and get to a better state of functioning, it WILL be worth it, more than you can imagine. You have to give yourself a chance, you just have to. The fact that you are even here proves that you have something in you left to give. And kudos to you for thinking before you act! That is NOT a sign of a dysfunctional or terrible person. I think you are a very intelligent person who know when they need help but are in circumstances that make it seem impossible.
Don't beat yourself up for how you feel about your children. I am currently fighting severe pregnancy phobia as part of my OCD and I have severe issues surrounding it. I have always felt guilty for not liking children or wanting children but I know that the guilt comes from society and it isn't reasonable. We are told as women that we HAVE to WANT children and LOVE them. That sound great and it would be wonderful if we could turn our feelings on and off like that but we are not robots, we are human. Sometimes we feel certain ways that other people may find unacceptable but that is their problem. We are who we are inside and all we can do is try to change it. I have no doubt that you love your children. You just feel like you are very overwhelmed right now and you want some time and space to work on yourself. It is very hard to do that with a husband and kids...so therefore they frustrate you. That is okay to feel that way.
You talk about how lucky you are to have your family, and maybe you are. But they are also lucky to have you! Those children wouldn't be there if it weren't for you and your husband would not have the life he has without you helping to make it happen. I also think that maybe they are not giving YOU all that YOU deserve. Your children sound like they are too young to even understand any of this, so you should't place any responsibility on them for anything. But your husband would have to be blind and heartless to not see the pain you are in. I am sorry but sometimes you have to make the first move and get some dialogue started between the two of you. It may make him angry and dismissive, but you have to keep trying. You can still get yourself some help even if he never joins in. Remember, just because you have lived a certain way for your whole life, does not mean it has to always be that way. Even if you can't fix past mistakes, you can stop making them and live differently from this point on. Your mistakes do not have to consume you forever, they just don't. You really need to try to tell your husband about some of your feelings. I trust that you are intelligent enough to know how to tell him and when. Even if you can't bring yourself to do that, at least tell him that you are considering getting some help, you don't even have to explain any further. I really hope that will give it a chance because I have a good feeling about you.