How to handle my Sister In Law

My sister-in-law and I have never really been friends. She's older then me and have always hung out with different groups of friends in different cities. We say hello on holidays and kind of chat on FB. 
She is going through a divorce from her husband of 12 years (a lying cheating abusive SOB). Through this process my in-laws have funded her lawyer, expenses with her 5 kids (the SOB is refusing child support), payed her mortgage, etc. 
This isn't the first time either; they have paid for things before. 
For 12 years, they have paid for her utilities, food, school clothes, car repairs, etc because she "didn't have enough money" (he was pocketing the cash for himself leaving kids without food and purposefully kept her in the dark). 
The divorce isn't finalized (he's being an SO B) and she is already in another relationship with a man she met in a domestic abuse survivor support group...and now she's 3 months pregnant with this new guys child...who she met in February...
She doesn't work. Neither does the new guy. And now there will be 7 kids. 5 of hers. 1 from him. And 1 from both of them. 
She announces her pregnancy to the family via text and is texting us "did you receive my text?" "What do you think?" "We're so happy."
I honestly don't know what to say back. My husband is obviously very upset and I think she is a complete idiot for 1) getting in a relationship before the divorce was finalized and 2) not using any birth control. 
She not telling her kids (as there is already a custody battle for them) and my in-laws are saying nothing about it but "don't judge her, you've done things wrong before too..." 
We didn't get pregnant right out of high school with no education and had a shotgun wedding to cover up the pregnancy. We didn't have our first appartment, trade school tuition, groceries, utilities, car, cell phones, health insurance paid for by our parents/in-laws during our first 5 years of marriage and had continually gone to Bank Mom&Dad to pay for things. We didn't buy a home we couldn't afford. We are not forcing our parents/in-laws to take out their retirement and investments to pay for our divorce, private school for our children, and other items because we are not changing our lifestyle because we don't want to let our friends know what is going on. 
So yeah. I'm trying not to judging...I'm just observing. 
And all of this, my mother-in-law has informed us, is because she loves her children and is helping her daughter. 
1)Do I even acknowledge her text back? What do you even say?
2)How do we let my in-laws realize they are enabling her, not helping (but at the same time she truly needs money for food for the kids)?
3) How do I help fix the relationship between my husband and his sister as he has stayed we will not be going to family holidays this year if she and her new guy come (and this is our LO first Christmas...)?
This whole thing is just a mess.