Need advice PLEASE! I'm 37, boyfriend is 46 & I'm divorced w/3 Angels.

I just found out I'm pregnant. My boyfriend & I moved into a relationship quite quickly...even share a beautiful home in the mountians. I have 3 beautiful children, whom I am in a very stressful custody battle with an abusive, millionare ex husband. I love my children so much, my heart hurts every day I am not with them. My boyfriend was told at the age of 30 that he had about a 0% chance of having children again. (Obviously a surprise to him!) I was laid off last year from a wonderful job, and have had such a difficult time finding another. My boyfriend's children are grown & has grandchildren the same age as my youngest. He sees this as a second chance, a new beginning. I'm terrified of my ex using this sudden pregnancy against me in court, as irresponsible & therefore having another ace in his pocket to use. My last two pregnancy's were difficult...gestational diabetes (and I've always had a good diet & remained thin), and both were born over a month early. My last pregnancy I was on bedrest from 28 weeks, and thankfully she held on to 34 weeks. With each pregnancy my cervix thinned faster & faster. SOOO, I'm a ball of emotions, stressed, confused & scared. I cannot imagine having another baby right now....but I've been through the alternative & I'm scared. I'm so fertile I swore I would have to ban sex altogether! Do not have anyone close to talk to, and God Bless my boyfriend, he's forgotten how emotional we get. I feel so alone & confused...any advice would be more than appreciated. Without my job I unfortunately lost my Health Insurance. To add insult to injury, sadly my BF's grandmother...who adopted him at birth...passed away on Mother's Day. According to my calculation...our baby was conceived that day...or a day before. All so much for me deal with....I hope I'm not alone. Thank you for your time & God Bless.