I think neither you nor your DH are being unreasonable.
This isn't what I intended when we got married and when I got pregnant. I want two parents raising our son not just me
I think this is the problem- you are looking at things entirely from your point of view- what you want, what you planned and how you think things should be. He is doing the same. There doesn't seem to be much partnership or conversation going on.
Obviously, I don't know whether you discussed things like job changes/childcare etc before you had your DC or not, but things do not remain static forever and sometimes both partners need to be open to change.
You can be a good parent and have a job with long working hours. I am a Dr and I know that this means I haven't always been there as much as I would like, but I am still a good parent. I'd be pretty pissed off if someone told me I couldn't work long hours and be a good parent. I think starting any conversation relating to the job with "if you take this job you'll be a terrible father" would be a massive mistake.
You need to sit down and calmly work this through. You need to explain your concerns, e.g. being worried about how you willl manage if left to do the vast majority of the childcare, and that you don't really want to live like that; the impact on you and on your relationship with DH if he is away a lot/working long hours; and also the impact on your career of having to pick up so much of the slack. Then you need to think about your DH. What will this new job mean for him personally and professionally- and what would it mean for him and his career if he turned it down? See if you can come up with strategies that would mitigate the impact on you that are acceptable to you both. Your concerns are completely valid, but there may be options open to you that are an acceptable compromise.
Ultimately, I think if either tries to impose their will on the other (i.e. him taking the job when you aren't on board or you attempting to force him to turn down the job) it will lead to resentment, which is highly likely to cause problems in your marriage.