Future mother-in-law

Any way, we told my family and his yesterday. Our family is beyond excited and supportive, except for his mom. She's never liked me, but nothing has really happened to make her hate me or vice versa. I wasn't expecting her to be over joyed or begging to help plan a wedding, but I never imagined she could be so hateful and heartless.. The first thing she said was that it was the wrong decision. She said that if it's because I'm pregnant (I'm not) that it would be the worst mistake her son has ever made. She went on and on just saying negative and hurtful things. I told her that I was very sorry if I had ever done anything to disrespect her and that I'm very greatful for the amazing man that she had raised. I told her that I really wanted to have a relationship with her and we both wanted our families to be apart of this. She said we would never have a "good" relationship and that it would take "tremendous work" on my part to make her like me.. Personally, I don't think I should have to because I don't remember doing anything to make her hate me. When I tried to apologize for the way she felt, she just shut it down. My fiancé was extremely upset, and I was for him. I felt really bad because everyone, including us were so excited. I'm at a loss because she is his mother and my future mil. I have no clue what to do and I feel really guilty because at this point I don't even want to be around her 😪