Co-parenting dilemmas. Need advice

So we're new to co-parenting. Will trying to at this point. We broke up a few months ago due to infidelity on his part and it's been a struggle. He is over the relationship and has moved onto another one, whereas I am still heartbroken and not moved on in the slightest.

So our agreement is he sees the children 2 times a week. That's all he wanted so that's our agreement.

Our twins are having their 5th birthday on Tuesday and although it isn't a day we agreed on he said he wanted to see them and I agreed to him coming for their birthday day.

He has now said he won't be seeing them on their birthday as he is busy and will see them on our agreed day.

How am I supposed to feel about this? I'm so upset especially when he goes above and beyond for other people.