Anyone had problems with older DC's????

[Foxeym]

I don't know if anyone has any advice but I'm currently 15 weeks pregnant with DC3 at the grand age of 42 (unexpected). I have 2DD age 15 and 12 who at first seemed ok with it all but as time has progressed, the older one especially is showing her true feelings.
She has said that I am selfish because she will have to study for her GCSE's while a baby is screaming etc and that she isn't going to share her bedroom and I didn't I think of her before I decided to keep this DC3 and I should have terminated it!!
I now feel really down and have been dwelling on what she has said, I am happy to be having DC3 but i now also feel that maybe I have been a crap mum by putting this on my DD's and not taking their feelings into consideration.
Am i being to hopeful to think she will eventually get over these feelings when DC3 is born (I have involved them as much as poss already, taking them to scans and letting them choose stuff etc, I'm also helping her as much as i can with her GCSE study and probably over compensating too much). I think some of it might be down to normal teenage angst, she isn't the easiest of girls to deal with but I am worried that things won't improve.
Has anyone else been through something similar???? Thanks

Hi foxeym OH yes i know where you are coming from I'm also 43 and and BFP was very unexpected. .... My Dd1 is 25 and is was really NOT happy about this baby. She even said that i should sell the house now so she could have 'her share' as this baby should not get any!!! OH i could have slapped her face for that. she has several step siblings and loves them all a lot. she is very happily married and is also expecting her first baby a few months after me. her problem now is that i won't 'be there for her when her baby comes' and i have 'stolen her moment' She too is a difficult selfish spoiled brat at times.
i'm new 28 weeks and she is slowly coming round, i focus on her needs a lot. I did in the end tell her that she was being bloody selfish and that this LO would recieve the same love and attention from me that she and her sister had and she would just have to deal with it.
there is a 40+ mums thread on here, lots of us have older children and unexpected BFP's lots of help, support and good advice on there, pop in for a
good luck and i'm sure she will come round when there is a little one to snuggle and show off to her friends.

I am having jealousy issues with my 6yr old,I tell her I love her all the time and really spoiling her. I've now decided to be firm with her as her behavior is getting worse,she needs to know that the new baby is just as loved and important as her...I am actually dreading the tantrums ahead! I don't have any experience of being a mother to a teenager but I am going for firm no nonsense approach as sympathy and treats/being spoiled has made things worse! Good luck!