Please help! My younger sister is pregnant at 18

Please help! My younger sister is pregnant at 18Please I need your advise.God bless,please don’t post ..Good evening , i’m a quite reader good work you’ve been doing ..my problem right now is my younger sister she was raised the right way, good girl and everything never joked with school and still doesn’t and she is just 18years old, she met a guy they’ve been dating since last year she just recently told me about it,I said okay it’s alright but she should be very careful and I educated her on everything she needs to know what to do and what not to..she is just about to start school,I just found out that she is pregnant,I’m so confused I don’t even know what to do.i met the guy he is serious about her and is willing to marry her and he is ready to take care of her he has a good job and everything and wants to settle down quickly that was why he got her pregnant (his reason) so I don’t know if I should agree to this his proposal or let my sister stay home but if she does there will be shame on the family.the guy is ready to bring his family to come and perform the rights I asked him why he didn’t do this before getting her pregnant he said he really loves her and knows we won’t allow her get pregnant or marry such at young age.he has sent her to catering school now and is ready to set up a business for her just for now until after the child then she can go to school later ,that before the child is born he’ll be working from home so she can go to school. I don’t even understand what’s going on right now please what should I do