Hello and thank you for contacting us.
I am sorry to hear about the problems you are facing. It does sound like a very difficult situation you are in. You may have read about shyness, that it can be part of someone's temperament. So there is a chance that your daughter will always have this predisposition. However, the circumstances you are referring to may well play some role in this. Children tend to need more attention when they pick up that there is something wrong in the family. One way could be to complain about not being loved, as she does. They might be using this also as a form of distraction to the parents from their own problems e.g. complaining about not being loved could stop parents from fighting and give their attention to her. It is also possible that her complaints of not being loved is an expression of her insecurities especially if she is somewhat aware of the problems between you and your husband. Finally, you described your husband as distant and possibly indifferent. So your little girl may well be picking up his feelings and may be feelings rather rejected.
if her distant and withdrawn behavior at school is reported to coincide with the beginning of the problems at home, then it would be safe to assume that she is affected by this. However, you would need to talk to the teachers and find out a bit more about her behavior and mood there, if she interacts with other children and whether there has been any change in her behavior. You might also want to explore about her difficulties concentrating at school.
The other thing that you mentioned that "you are losing control" this is not very clear what you mean. In all cases, since you have entered a difficult phase with her father, the environment needs to stay as relaxed and safe as possible. You both would need to avoid fighting and arguing in front of her or where she could listen to you. You both would need to show her love and affection so when the final change happens (one of you moves out) she still feels contained and safe. This would ease some of the effects of the divorce on her. I think that you are in a very difficult position especially since as you say you feel that you are the only one that is concerned. You are a very good mother and I am sure that without your help, your little girl may have had more problems. However, your husband needs to help you out in this and you also need to engage school as well.
I wish you all the best and hope that everything works out well for you and your little girl.