I am seeking an attorney who is knowledgeable about QDRO's

I was divorced in 2014 and my X-husband passed away of brain cancer in 2016. Included in my divorce decree, it states that I receive 50% of his 401K plan. However, my divorce attorney never had the QDRO prepared or signed and neither did he have a will prepared. I am unclear as to who is responsible for these errors. In addition, even though I was named as beneficiary on his group life insurance, my X changed the beneficiary from me to his mother while having over 30 brain tumors which were inoperable. There is no doubt in my mind that his mother convinced him to do this. I am unclear as to whether this is even legal since my name was on our divorce decree. I am now in the process of withdrawing from his 401K. I have went over the form with the company who is handling this. They have received a copy of the form which they helped me prepare with the exception one answer which has to do with an outstanding loan in the amount of approximate $4,500. More to discuss, but no room