Okay so… after your updated posts, it looks very clear that the proposal is just a tiny symptom of a myriad of major relationship issues.
It sounds like you’ve been trying to analyze yourself and your outlook to try and refocus and get perspective on your life because you think you’re feeling depressed when you shouldn’t be (like when your husband tells you that you have “no reason to feel that way” and it sounds like you believe him), and if you just get a better perspective and be realistic, you can be happy. That makes sense and is an admirable effort because perspective is incredibly important, and people can get into negative mental spirals very easily and obsess over things that don’t matter. However, if the problems are realistically elsewhere, then you’re just going to beat yourself into a pulp and drive yourself crazy over things out of your control and possibly invest yourself deeper into a very unhealthy relationship.
From your description, he sounds controlling and apathetic and completely disinterested in your feelings, which does not represent a good husband. Again, I don’t know him or the relationship, but from your words he doesn’t sound like a very loving husband, nor did he sound like a loving fiance, actually.
You need help, and your husband probably needs help also. You sound very dejected and depressed. From how he acted throughout the whole wedding-planning process, it doesn’t sound like he cared about your feelings from the beginning. That cake issue? That’s a big red flag right there, unless there was some horrible miscommunication. You said you wanted ONE thing: a dream wedding cake. You even had most of the money ($1,200… which, if you gave up your career, how did you save for that? Do you also work? IF you also work, then why is he “allowing” you to get your hair done for your birthday?), and all you needed was $400 more. Not only did he refuse, but then he turned and spent like $720 on a separate cake? What?? That shows some crazy serious selfishness right there on his part… and concerning you… I’m very worried about your self-esteem. If what you’re saying is accurate or mostly accurate (I’m in no way saying you’re purposely trying to be misleading, but sometimes one side of a story looks very different from the other just because of emotion and perspective), then I’m afraid you’ve possibly have married into a emotionally abusive or at least emotionally devoid relationship with a very selfish guy.
I’m also very concerned that he is IGNORING your requests to avoid having lunch multiple times a week with this woman. I’m not sure if it’s true or not, but a ESPECIALLY a woman who is known to try and snag married guys? That’s… really bad. If it means nothing and is casual, he should have no problem respecting your request out of love for you (especially if the information about her is true). Just because they go out with a friend now doesn’t mean that it won’t become just the two of them very soon, or happy-hour-after-work, etc. That’s a slippery slope especially when it sounds like he doesn’t really care how you feel…?
So I must ask… Why did you want to marry him? Was it because you had kids and he was a great dad? Because it doesn’t really sound like he does much for you, emotionally. It doesn’t sound like he concerns himself with you or how you feel… But I have to ask if there is more here. Or why did he want to marry you? Do you know the reasons for this on your or his side?
Did you have kids with him before getting married? Is it possible he just felt obligated? Or that you both felt obligated? Did it just seem like it made sense because you had kids, been together, lived together… ?