<human>: Condense the text into a few key points

We're attending an event for our daughter (5) that is a 4 hour car ride away.  We will be driving together, and also staying in a hotel together, and I'm looking for some advice on how to prepare for it.

Backstory - ex was charged with domestic assault after she attacked me about 1.5 years ago. We split up, she moved out, and we split parenting time with our three young children.  The custody battle is over (16 months), and I'd love to have a normal adult relationship with the mother of my children. Unfortunately, she is very manipulative, controlling, and has sudden outbursts over insignificant things. 

She's a selfie addict, and loves to post about how she is "such a hot mess today" as she's driving the kids around from one activity to another (she lives solely on my child support, going to school part time, not working).  Everyone around us only sees the beautiful, single mother that is working toward a degree and doing what needs to be done to make ends meet. I have to deal with the dishonest, controlling, ex-alcoholic in private, but have to put on a smile when we're in public. 

I just need help preparing myself for the inevitable attempt to start a fight, stories about how hard things are for her, and how difficult the children are to deal with (when they are at my house there are almost zero discipline issues, at her house they break things, fight, and don't listen). She uses her looks and sympathy to get things from others, and I admit if she turns on the charm with me I have a hard time remembering all the horrible things she did during our relationship.

Any strategies or recommendations for dealing with an ex over a three day weekend event?
<bot>: Need to spend a weekend with my ex for an event for our daughter. 4 hour car ride each way, same hotel room.