Weird behavior from the ex

So my ex and I broke up almost 3 months ago. Not a bad breakup, per say. Just unexpected on my part. We’ve managed to at least be civil with each other because I babysit his nieces(sister is my bff) quite often when him and his sister are both at work. We talked for a while, but then he abruptly started ignoring me. He’s avoided coming to our church at events/ministries he knows I’m part of, but he was going through a lot at the time of our breakup, so I figured maybe he’s struggling.

He finally showed up to the YA ministry where we met because him and sister had to plug a ministry team they’re launching at their location(our church has several multi sites). He apparently didn’t want to come. He stayed for about 2 songs of worship, then left. Maybe he went to the bathroom? No. Didn’t come back until about 10mins left in the sermon, and even then he stood in the back with his arms crossed. We leave and start socializing. He stays pretty much glued to his sisters side, super close to me, yet doesn’t say a word except for “drive safe” when I finally say bye to sister and the nieces. He’d also been looking at me/in my direction the entire night.

My guy friends say he’s probably realizing now what a mistake he made(he broke up with me) and is grappling with that or regretting it or wants me back. But idk. Help.