Stuck in a depressed rut

Lately I’ve been feeling depressed with my everyday life and I don’t know how to get out of this rut. I was unhappy with my ex and broke things off with him, since then I’ve been a solo parent physically, emotionally, financially with no help whatsoever to my 5 and 7 year old. While he has moved on from his responsibilities, found a new girlfriend and a child to take on while they have a baby on the way. He made my life so miserable and even more so after I left him while he lives the happy life he chooses. I’m even too scared to get close to anyone because of the trauma I have from that relationship. Most days I’m normal and fine and have no complaints on life, but more so lately I’ve been feeling quite down and I don’t want to continue feeling this way but I don’t know how to cope with everything on days like this 😢