I have a problem and need some advice but don't want to start a whole thread about it so thought I would ask you guys....
Background - while at uni and for a while after, I was in a relationship with a guy called Dan. One day, after about 5.5 years, he decided he was leaving me for a mutual friend and left. I was distraught at the time but obviously got over it as I met and married DH about 3 years later - yey :)
When Alex was almost 2 (so about 6 years after break up) both ex and I were invited to a friends wedding. I can't say I was keen on seeing ex again but I really wanted to go and celebrate friends wedding and was taking DH so I figured I'd just have to get over it.
Ex had other ideas and threw a strop. Told friend he wouldn't be attending the wedding if I were going to be there! Friend had organised 2 receptions, 1 straight after the wedding and 1 once they got home from honeymoon to which we were both invited. He ended up having to ask me whether I'd mind not going to the 2nd reception so that Ex could go to that one. He was obviously embarrassed at having to ask and I agreed not wanting to make his wedding planning any more difficult. As it was, ex didn't turn up to the 2nd reception anyway citing expensive hotel rooms as his reason 
Tonight, another mutual friend has sent me a message asking me if I'd like to go to his wedding reception. I really would as it's not often I get to see this group of friends because they live so far away. I've said yes but then thought 'but what if Ex is still playing silly buggers?' As far as I know, this is 2nd friends one and only reception and I'd hate for it to be made complicated because of me however indirectly.
So, my question is - do I say nothing and see if Ex is going to cause another song and dance about being in the same room as me or do I warn friend and give him plenty of notice to potentially uninvite one of us?
I don't want to be the one causing problems but I would rather save friend 2 the hassle of sorting things out at the last minute if Ex does play up. It wasn't my fault last time but I still felt awful at causing friend so much stress in the run up to what was such a happy day anyway.
What do I do?