Yes she's threatened by you, or more accurately, not being able to control you.
Yes you will be cast as the bad guy for not letting her take charge. The trick is to simply not give a shit.
There was a brilliant post on here a few months ago about someone who met their future Mil for the first time with the rest of the family at a restaurant or pub for a meal. When everyone had gone to the toilet/bar, future Mil turned to the poster and said "I don't think I'm going to like you very much". The posters response was to look her directly back and say "So?"
This is the attitude you need to have.
Every time you stand up for yourself you will be painted in a bad light. It's important you understand this. Every. Single. Time. But don't be drawn into justifying or explaining yourself. It won't work. She will attempt to draw your DH into the emotional blackmail too. That's why saying 'we' a lot is very important so that decisions come from both of you.
It sounds like she wants to feel in control of your DC in particular.
Be one step ahead.
Make plans for holidays, bank holidays yourself. Don't let her take control and call the shots about how family time is spent. Get in first, and always have a plan.
Be careful accepting gifts, return any unwanted or very expensive ones:
"Thank you, but this is too much. As discussed, we don't give expensive gifts outside of birthdays and Christmas"
"Thank you for your kind offer (money) but we have got this covered. We'd like you to keep this for yourself"
There will be attempts to control you disguised as acts of kindness.
My inlaws had a xmas tradition of the DH in the family dressing up as santa to hand out gifts. Mil sent me the adult Father Christmas costume telling us that now we could follow the same tradition.
I sent it back with a note saying "this is a tradition your family did, in our family we have some different traditions. Thank you, but please keep this as a momento for yourself"
My DH got an earful about how unkind and ungrateful I was, but I ignored it.
Turn down offers of free childcare.
"Thank you, but we have got childcare sorted. We would like to arrange a visit for you to see the DC on xxx though"
Please understand that any acts of "kindness" will be used against you when you come to blows over anything big: "but after everything I've done for you!"
There is a brilliant book you should read called 'a wolf in sheeps clothing' it's all about manipulative, controlling people and how to defend yourself against them.