Personal experience - the IRS did not get involved when a spouse signed another spouse's name, they were no help whatsoever. If it becomes necessary, you could get a copy of the return from the IRS and take him to court. Look for free legal aid in your community (possibly at a university with a law school), or a free consultation with a local attorney for advice.
Some banks check the names on the bank account, some don't. Call the bank if you know where it's supposed to be direct deposited and ask. If it's rejected he'll get a check made out to both of you, but again, if he forges your name on the check don't look to the IRS for help.
Just a thought--you may not be entitled to 1/2 the refund, but whatever amount exceeds what he would have gotten if he filed single.
PERSONAL ACTUAL EXPERIENCE, THE IRS WOULD NOT HELP WHEN SPOUSE SIGNED THE OTHER SPOUSE'S NAME AND DIRECT DEPOSITED IT INTO HIS ACCOUNT.