How To Reduce The Stress Factor In Body?

I ve got a bad problem in the head, I always stress out and loose it over small stuff or big, I was ok not perfect before my children were born but ever since I ve seemed to become someone else, I dnt sleep much and I dnt eat as much as I should my partner suffered with postnatal depression for 2 yrs so I done pretty much everything I ve noticed the stress started back then but just got greater and greater