Letter to BIL

I'm seeing my MIL tonight and I am giving her this letter:

BIL,
We hope you will take the time to read this entire letter.
When called last week and asked if we would take (the children) it caught us by surprise. We told you we were going to have to make some phone calls to see what rights we had and what steps needed to be taken. Of those phone calls the first was to our lawyer who recommended we contact (Children's Services) to look into the program where children are placed with family members. After you had indicated SIL wanted to give custody for only a year we told you that we would only do that if (Children's Services) was involved since we would receive financial support. Since you said "SIL needed to make a decision by September” we made the call intending to discuss temporary custody however this turned into a discussion about why you were looking to give up the children. As such, a report was filed and they said they would be following up with you. They indicated the information we had provided would not result in the removal of the children. We also made sure you knew as soon as possible exactly what had happened.
We sincerely hope that you will take this opportunity to discuss your issues openly and not hide them to protect SIL (or yourself). We strongly feel you are in a situation you can no longer control and giving away the children is not the solution. Further, the thought of SIL saying she doesn’t understand “why we’d want them” concerns us greatly. She is sounding desperate and we’re beginning to wonder if she has Postpartum Depression.
BIL, we want to help you however it feels like you do not want that help. Your inaction makes you part of the problem. When your mother calls us it is always new stories about something SIL has done and how awful things are. It’s getting really old since we’ve been hearing these stories for years – even before your children existed. We do not get any pleasure from this gossip – it makes us ill with worry. How are you ever going to stop this? Have you called the lawyer yet? Do you understand your rights or are you only relying on information you’ve read online? We doubt things are going to get any better if you continue on your current path. The children are getting older and will act out when they begin to understand what is going on. (Nephew) is already getting a bad attitude and that isn’t funny at all, it’s very sad.
We would also like to address the statement that we have a “motive” that we are trying to take you children away from you. Our carrying cost on the condo is in excess of $****/month and we both work full time to support it. Do you know that when you asked if we’d take the children the first thing we did was look at our finances and we determined that to afford daycare for two young children in Toronto we would have to sell our condo and move into a rental unit? Do you also know that we would still want to have our own children but discussed waiting at least 4 years to make sure (Niece) would be in school? Does this sound selfish to you? Does this sound easy or fair for us to give up so much? So please do not accuse us of trying to steal your children.
We’re not sure when we’ll see or hear from you next. We understand that you are upset. All we can do is wait and hope that you do not turn your back on your family who loves you and wants to help you. You may not see this as the right thing now but we hope that it brings around a change that will make your life better.
We’re here when you’re ready.