Given your age and length of marriage, you would be entitled to receive alimony.
You would be entitled to an equitable distribution of any maritial assets obtained and/or contributed to during the marriage.
You should also be able to make some kind of deal for your health insurance.
Unfortunately, you will not be able to use the fact that he was previously married or that his mother "divorced" him (whatever that implies) since you admit that you learned this shortly after the marriage and you continued to stay married to him.
As for obtaining legal assistance, contact the Bar Association, Legal Aid, Senior Services, etc.
If you air your dirty linen in public, expect people to comment on the skid marks!