You and your man come from different families, with unique histories. And it is important that you understand the particulars of these histories and how they have influenced each of you. He must be ready to make his relationship with you his number one priority. Life will be easier if your husband is prepared to establish healthy boundaries with his mom from the get go. If he does so, he has taken the first and most important step in paving the way for a great relationship between you and his mom.
Blood is thicker than water.
If his mom oversteps your boundaries or says or does something hurtful, your partner should be prepared to address it with her. She may not like it, but she will forgive and forget. If you approach her yourself, especially before your relationship with her is on firm footing, she may have trouble forgetting your words. If, despite his best efforts to set limits with mom, she continues to overstep your boundaries, he must be ready and willing to help you put distance between you and his mother. Look for areas of common interest and, at the very least, meet her for coffee from time to time.