S.,
I am sorry that you are getting so blindsided and that you and your children have to go through this.
I don't know any delicate way to say this, but it sounds like he is moving on to a new life and wants to do that without any commitment to you and your kids. What a horrible deception for him to have pulled on you and how callous the disregard, not only for you, but for all the changes your children have had to endure recently.
Today---talk to trusted friends or co-workers to see if they can refer you to the best, most experienced attorneys who practice family law in your area. Do not ask any mutual friends because you don't want this to get back to your husband.
Don't even mention this or the word 'divorce' to your husband yet because it may send him into a more aggressive mode, legally speaking. He's busy with the job and move stuff now and probably figures he has a little time. In his mind, he already knows what his plan is and figures you'll be so behind the curve that he'll have the advantage. So, take this time now to do all of the behind the scenes information-gathering you need to do to protect yourself and your children.
Tomorrow, make calls to a few of these attorneys and have appointments set to meet with them before you make a final choice. Again, do not mention this to your husband at this time. As hard as it might be to keep quiet, you have to see how important it is to use this time to your advantage to get all of the information you need to have the best chances possible.
I don't know the laws of your state, but if you have only been married a short time, alimony likely won't be on the table. However, that does not mean that you cannot get some sort of fair settlement in the divorce. That's why you need to trust the experience of you attorney and why you need a really experienced one.
It sounds to me like he wants you to get a higher-paying job now because he wants to use that information in the divorce proceedings to prove that you don't need any sort of settlement from him to live. While you will probably have to get a better paying job if you do divorce, that doesn't have to happen at this moment. This is where the advice of your attorney will be helpful regarding what you should do.
I truly am sorry for you and your kids, and while it must be so hard to sort through all of your feelings about this betrayal, it seems like going into self-protetive mode is your best option at this time. Call your best girlfriends for support; call in the attorneys for your defense.
J. F.