The Tier 2 policy guidance states that when you resign from your job, your leave to remain will be curtailed "to 60 days starting from the date the decision to curtail leave is made". In other words, once UKVI find out that you are not in employment, you will have 60 days to leave the UK (or find another job, or switch to another visa, but you don't want to do that). So as far as staying in the UK after resigning, you should be fine.
Where it gets tricky is reentering the UK. Border officers tend to heavily scrutinise people who are returning to the UK on a visit very soon after having held a long term visa. They suspect that such people may be trying to continue living in the UK. Bear in mind that this also applies if you try and re-enter the UK after your leave has been curtailed. The border officer has the discretion to reject you even if the curtailment period hasn't finished. Since the premise for your leave no longer exists (you don't work in the UK anymore), the border officer may be inclined to deny you entry. In this case, you could end up being returned to the USA, possibly being detained overnight depending on the timing of your arrival.
In your case, have several options. If you can time your resignation differently, you may be able to ensure your leave isn't curtailed until you return to the UK after your February holiday. It may take some time for your employer to inform UKVI*. But it is perhaps a little risky. If your leave is curtailed while you are away, you could end up in the situation I described above.
Or you can ensure you have plenty of evidence that you are in fact just visiting, and will leave by March. This would include evidence of your husband's job, and where you plan to live in the US. Expect to be questioned intensively on why you are still in the UK despite no longer working here, and be prepared to explain exactly what the purpose of your visit is. The explanation that your husband got a new job in the US, but that you already had this holiday booked, therefore you are returning to tie up loose ends after the end of your holiday is very reasonable and convincing. However, border officers can sometimes be intimidating and rude, and it is down to your ability to convey the explanation calmly and rationally to ensure you are allowed to reenter.
Actually, it would be best to do both things. Try and avoid reentering the country during your curtailment period. But be prepared to present evidence that you will leave the UK by March.
* Your sponsor is obliged to report your resignation within 10 working days of your departure. Depending on your relationship with your employer, you might feel able to ask them not to report your resignation a day sooner than this. And if you resign on a Friday, and your resignation is reported at 16:30 a fortnight later, likely your leave wouldn't be curtailed until well into the following week... Even if you don't feel able to ask your employer to assist you in this way, resigning on a Friday is probably a good idea to maximise your leave.