As you said that your mother has taken lot many pain for your raising. I am sure that she is worried about your future with that guy. She has already taken lot many pain as a lonely parent and definately she does not want you to face problem in your life. So you should give importance and respect to her feelings.
First of all you should understand that why she is not accepting that boy. Is religion only matter for that? If so then you should talk to that boy and put her points in front of him. Because everybody has their on believe and everybody should respect that.
Second, what about that boy family? Will they accept you? Are there any terms and conditions for accepting you? These points must clear.
Third, do you believe that this boy is really loves you or this is only an opposite sex attraction? Because as time passes that attraction will disappear and you will be in big trouble.
My suggestion is that try to find out the answers of above mentioned points. If everything is positive then you should sit together with your mother along with that boy and convince her. Also understand the openion of that boy’s family. Most important point, Please do not involve physically with that boy.
Last point: your mother has already struggled a lot for your upbringing. So do not be so selfish and leave her alone. You have not taken birth in this world to love a boy only. You have taken birth to give proud to your parents.
Let us all know about your decision. I am here to discuss this with you in detail.