baby measuring about 3 weeks behind

Today I suppose to be exactly 9 weeks pregnant, but just found out the baby is measuring 6 weeks 3 days with a slow heartbeat of about 50 which Is down from 90 two weeks ago. They just basically told me to start thinking of which option I'll choose to clear things out when the heartbeat finally stops. I can't stop crying. This is my 4th miscarriage in addition to 1 preterm birth& this is my first IVF. I just want to tell heaven & earth how unfair this is. I don't know how I'm going to carry on in these next few weeks. Even my husband is now so tired of this recurrent miscarriages. I feel like such a huge failure and my world seem so dark in front of me.