I don't want my MIL to babysit my son (15 months)

Hi everyone -I've seen posts on here before about the benefits of cultivating a good relationship between your children and their grandparents, which I think is great in theory. I'm struggling with my in-laws and their request to take some time off work and watch our son instead of sending him to daycare.My son is 15 months old - from the start he was a very colic-y baby who cried for months straight when he was awake. He's a wonderful little guy but still apprehensive in new places/new people which is normal for this age but he seems more uneasy than his peers.My in-laws are very tough love with him, right from the start. My MIL would just look at him crying as a newborn and suggest 'there is probably something really wrong with him. The only thing you can do is put him down and let him cry'. Right or wrong - I feel comfortable with the totally opposite approach, so that's what I did. Now that my son is older, they're very harsh with him (in my opinion). They're always telling him to 'stop crying for mommy' when he's uneasy at their house (they won't stop wearing strong perfume and smells really trigger him). There have been a few accidents which resulted in him getting hurt when they are around, which is totally understandable, but instead of offering him any comfort at all, my MIL just gets close in his face and tells him 'get a grip!'. She can't seem to differentiate at all between a pain cry and non-pain cry. She also referred to him exclusively as lard ass for the first year of his life and dropped not subtle hints that he was too fat and hopefully he would slim out soon.Anyway - none of these things are life threatening, but now that they've asked to watch him, I feel really nauseous thinking about my son needing any kind of comfort and I know he won't get it.For the record - while I really wish I was a SAHM, I'm a million times more comfortable with our daycare provider because I find her style to be very similar to mine - provide comfort based on age while still encouraging children to learn to problem solve.My thought is that I would feel a lot more comfortable (well - as much as i'm ever going to) if this happened when my son was at an age where he could communicate what was bothering him. I don't think waiting is going to impact their relationship too much, but I also can't tell what is reasonable vs. my 'mother bear' instinct coming out.So - advice? Did anyone wait until their LO was 'full toddler' before allowing them to be baby sat by certain family?Thanks! :) via /r/Parenting http://ift.tt/29WWKVc