In reality, your mother-in-law is the one who has the biggest problem, not you although I know it's hard to look at it that way. Yes, you have a problem, and I know it's real but if you stop and think about it, she has an even bigger problem.
What I mean is this: By her anger and resentment she's not only hurting you, but she is hurting herself. Bitterness is like a poison to our souls, and when we allow it to eat away at us, it destroys our happiness and turns people away from us. After all, no one likes to be around someone who's constantly complaining or angry. They are like the man in the Bible who "dies in bitterness of soul, never having enjoyed anything good" (Job 21:25).
And frankly, I doubt if any suitor could have made met her standards. For whatever reason, she would have resented anyone who "stole" her daughter. She never understood that God gave our children to us so they could become mature and some day set out on their own. Her pride and possessiveness are both unhealthy and sinful, and she'll never be happy until she repents of them.
The Bible says, "If it is possible, as far as it depends on you, live at peace with everyone" (Romans 12:18). Ask God to help you show love to your mother-in-law, in spite of her faults, and to fill both you and her with Christ's love and peace.