HELP!!! My mom will ask too much money from my boyfriend for our engagement?

My boyfriend and I love each other for 5 years now. He is such a good guy. He struggled every obstacles just to be with me. Everyone might say the first flirt is the ever sweetest time. But our long-love is even sweeter no matter how hard time we had together. Yesterday he asked his mom to ask my mom for our engagement since he proposed me last week. My mom said yes. I was so happy and thinking that my pitiful love that I've always taken care these many years with him is succeeded. Today my mom told me that she wants him to buy the engagement ring, bracelet, necklace, and earrings for me in that party. Also she wants him to keep his own money $15000 with her (because I am 17 so I cant have account) to see if later on he would change his mind or I might change my mind for this love. I am so confident with my boyfriend and myself. I tried to explain her that it is a lot of money for those jewelries, party and also deposit $15000. He has jobs, but you know life in America is so hard right now. For me I dont care much on his stuffs but his love and faithful which is so hard to find. I dont blame my mom on that because she might concern me as her daughter. She said if he wont have those stuffs, maybe we have to wait more til he has them to engage me. Since we were bf and gf, my mom never likes to be in that relationship. and now he proposed me (but we will marry til I turn 22 or 23) so we can be fiancees... now she needs money... I dont get why... and I dont know how to tell her how I feel right now... I wanna cry and cry... if she ever would deny our engagement, I will never marry or in relationship with other guys at all no matter how rich they would be... I believe in my love... I am a thoughtful girl who try really hard at school to get the better job and have a simple, but happy family with the one I love. I never have any relationship besides my bf. My mom also knows how hard he struggles for me, but she still need those stuffs... I told her we can make it later. the most important now I found the good person. She only needs bragging rather than seeing her own daughter is upset. she said she would tell her friends how proud she would be to have someone gimme such those stuffs... I dont care I dont care... and I dont understand why.... I am so depressed now... I start to feel like wanna dump my life with no love to the rich guys to get those stuffs for me to brag her friends and then I will commit suicide and let see if she ever happy with that.... please gimme some ideas... I am stressed now... I miss my bf so much...