Scared of another child after twins

Sorry for the long post...I am a 36 year old mum of five year old twins. Several weeks ago I discovered I was pregnant (unplanned). This was confirmed by blood test at doctors. Two weeks later I went for ultrasound which showed an empty sac and further blood tests revealed I was no longer pregnant so doctor suspected blighted ovum and told me to wait out the miscarriae. This all happened just before a family trip overseas. As I thought I was no longer pregnant I enjoyed numerous cocktails by the pool daily and a few wines with dinner. On returning from holiday I still felt pregnant so went to doc and low and behold a blood test and ultrasound confirmed I still was! I am terrified as to what my alcohol consumption over two weeks of holidays may have done (I would have been 7 and 8 weeks pregnant whilst on holidays). I have one child already with a learning disability and i'm terrified I have potentially caused another disability with the consumption of alcohol. This, and other factors are making me not want to keep the child. After raising twins, (mainly on my own as my husband works away alot), I was really looking forward to next year when the kids would be at school and I could get a part-time job and enjoy the next stage of the kids life. I didn't want to be 37 with a newborn. I love my two kids but really did not want anymore (and thought I couldn't have anymore due to contraception). I am crying alot and so unsure what to do. The thought of an abortion is terrifying but the thought of another child is even moreso which worries me more that I am thinking that way as I just can't get happy at the thought of another child and that makes me feel terrible. I wondered if anyone on this site had experienced anything similar and what decision, either way, you made. Also if anyone accidently drank at the beginning of pregnancy to, I would appreciate any stories you may have as to how your child is now. thank you for listening.