Daughter-in-law problems

My son recently remarried. I received an email from his new wife listing problems I am causing that she feels are effecting their marriage. There are many inaccurate assumptions in the email. I have not responded. I did text them stating I was brokenhearted that she was hurt by my actions. She feels I am too close to the family of his 1st wife. His 1st wife is the mother of the only grandchildren I will ever have. My husband and I have become close with the 1st wives parents and consider them to be good friends. I offer support to the 1st wife: taking care of the kids dogs when they are out of town, etc. The 1st wife has remarried and had a child that died of SIDS at 4 mos old. I feel tremendous empathy for any parent who looses a child. I believe, when grandchildren are involved, everyone should be forgiven and treated with respect and kindness. The 1st wife has supposedly been very rude to the new wife. 2nd wife does not want us to have contact with 1st wife & get all info regarding the grand kids from her & my son. Supposedly, the 1st wife rubs it in their faces that she & I have a 'special' relationship and this infuriates her. I want my son to be content and happy in his new marriage. Also, the 2nd wife cannot have children and the 1st wife has now had another baby.

(A) Thank both of you very much for your responses. I appreciate the input.