Thanks for bringing your question to JustAnswer.
What you're experiencing is a combination of grief and Post Traumatic Stress Disorder. Here are the symptoms of PTSD from the US Nat. Institute of Mental Health:
Symptoms of PTSD fall into three main categories:
1. "Reliving" the event, which disturbs day-to-day activity
Flashback episodes, where the event seems to be happening again and again
Repeated upsetting memories of the event
Repeated nightmares of the event
Strong, uncomfortable reactions to situations that remind you of the event
Emotional "numbing," or feeling as though you don't care about anything
Being unable to remember important aspects of the trauma
Having a lack of interest in normal activities
Showing less of your moods
Avoiding places, people, or thoughts that remind you of the event
Feeling like you have no future
Having an exaggerated response to things that startle you
Feeling more aware (hypervigilance)
Feeling irritable or having outbursts of anger
Having trouble falling or staying asleep
You might feel guilt about the event (including "survivor guilt"). You might also have some of the following symptoms, which are typical of anxiety, stress, and tension:
You would begin to feel much better if you found a therapist who specializes in trauma, and particularly EMDR, a treatment proven to work for trauma.
The fact that you're still living with the man who caused this trauma means that you are constantly being triggered by his presence. Even though you say you've been happy ever since, your symptoms say that deep down inside, you are having trouble trusting him, which is why you cling to him. You are still mourning the baby, and the nightmares are a result of the trauma.
Your symptoms are quite serious, but they can be treated with the help of an experienced therapist. Here is a link to help you find a therapist trained in helping persons with trauma. http://www.emdrassociation.org.uk/home/mapping.htm