Heartbreack, depression, too many responsibilities, suicide ideation - What can I do?

I was divorced for 12 years. I didn't expect to ever love like I loved my husband of 20 years. I have dated a lot but until last February I had never fallen in love again. Then I met this man that I trusted with my heart, We were to be married in January. I am the responsible one in my birth family. My father died suddenly. My mother is very sick. I had to do an drug intervention for my sister who lives across country. (It worked, but she is too flaky to be of any help to me.) I lost my job. I am in charge of my mother's physical care and trying to probate my Dad's will but he moved money during the stock market and I am having trouble following the trail and identifying their assets. Both of my children went through some serious marital issues. I have two handicapped grandchildren. I almost lost my home to foreclosure. My doctor prescribed an antidepressant but I can't afford it - no insurance with new job which pays significantly less. There were other problems but these are the high points. The man I loved bailed when he saw how difficult my life was. Four months later and I still can't get over him. I am not a kid. I am in my late 50's but I trusted this man to love me unconditionally as I loved him unconditionally. (He had some very serious health issues and I was accepting of these. HOW CAN I FALL OUT OF LOVE? I keep trying to apply logic to it - his health would take him from me in a couple of years, he probably wouldn't have been supportive of me in my struggles, etc. But LOGIC is not working. I am so overwhelmed with responsibilities and now I can't get over this man. Suicide keeps popping into my head. It isn't that I'd kill myself over him, but there is just so much that I can't handle the heartbreak on top of it. How do you stop loving someone who you know is totally undeserving of your love? I really don't want to consider suicide but I am exhausted and lost. I fall between the cracks financially for community mental health resources. Help me.