Overthinking & Pessimistic. Negativity.

Hello I am having constant negative thinking and being depressed, anxious, stressed about each and everything. Feeling something bad might happen to me, my husband or son.I couldn't take my usual fever easily. Thinking I am having some disease and running behind the doctor.  Complicating things by overthinking. All these have started after marriage and aggravated after my son's birth. I am so dependent now. I was never like this before. Very bold brave independent person who took care of the entire family by all means. Now I need someone to help me for each thing. I lost my uniqueness & identity. I always fear of having heart attack or that something could happen to me or my family. I had rough days in my childhood and adolescent age. Constant thinking of past and my family situations changed drastically after marriage like in laws and my parents changed completely different. My husband supported me, but still couldn't calm down and move on.  How to help myself away from negativity.