The first thing you need to do immediately is find an experienced immigration attorney in your area. There are many on this site who will do a free initial consultation. You should contact them by phone and not email.
With immigration there is always a chance, this may not be obvious to you, but a immigration attorney will be able to honestly let you know his chances. Make sure that you have copies of his criminal record and any other prior immigration cases he may have had.
Marc Taylor, Esq.
I agree that you should immediately consult with an immigration attorney. Your partner's eligibilty for various forms of relief will depend on a multitude of factors not mentioned in your brief summary of the case. Among the factors that an experienced immigration attorney will consider are:
* When your b/f first entered the U.S., and how;
* Whether he ever departed the U.S. after his first entry, and how long he stayed out, and how he returned each time;
* Your b/f's past immigration history, including any prior contact with CBP, or placement in removal proceedings;
* Your partner's past criminal history;
* Your criminal history
* The marital history of both you and your partner;
* Any health issues for you or your children, or other equitable concerns;
* Whether your partner was ever the victim of a serious crime;
* Whether anybody (employer or family member) ever petitioned for your partner in the past, and when;
* Whether your partner has any fear of returning to his home country, and why.
This is just a partial list, but should give you some idea of the depth of a good consultation.
Don't hesitiate. Once your partner is in immigration detention, things might move pretty quickly, and you want to be prepared. Depending on the facts, your partner may have to fight his case while in detention, making it all the more urgent to work with an attorney now to come up with a plan.
Both my colleagues already provided excellent answers.
I would just like to add what my father, who was also an immigration lawyer used to tell me (and his clients). Laws are man made and can be changed by man - nothing is impossible.
In my career I have seen some pretty "impossible" cases work out just fine.
Also, there's a now somewhat famous quote amongst immigration lawyers that goes: we win by losing slowly.
Don't give up hope!