Do I make amends to my exes?
If you harmed them, and you now want to stay sober, yes.
But what if it was a long time ago?
Then you apologise also for the delay in making amends, and explain why you're apologising only now, i.e. you're in recovery, and this is what we do.
But what if they're in a relationship with someone else?
Irrelevant. You're making amends to them, not propositioning them, courting them, or inviting them for a dirty weekend in the Cotswolds. If distance is necessary, write a formal letter, get it checked out by a grown-up, and make clear that you're only admitting your wrong, recognising the harm, and expressing goodwill and that there is no ulterior motive.
But surely raking up the past is harming them?
Step Nine does not classify an event being in the past as grounds for disqualification. If that were the case, no amend could be made, because the harms in question are necessarily in the past, and making amends necessarily rakes up the past.
But what if they experience negative emotion?
Of course they will. But if they do, you're bringing out negative emotion that is within them the whole time anyway. You're not creating new negative emotion. Step Nine does not suggest that we make amends for all harms except ones where emotion is involved. Again, that would reduce Step Nine to trivialities plus paying back debts to corporate entities. Remember, if they experience negative emotion, it's not because you're making amends; it's because you've hitherto failed to make amends. That's why they're upset. You treated them poorly and did not clear up the mess properly at the time. Your apology may be the missing piece enabling them to finally move on emotionally. Lastly, if they don't want to take the call, meet, or read the letter, they can say 'no'. You'll have done your part. If they're minded to be hostile, unforgiving, or shrill, that's their prerogative. You're not responsible for that.
So, go and make them, and get a grown-up to help you. Then you can become a grown-up, too!
Footnote: 'except when to do so would injure them or others'. You can only do this by (a) revealing new information (b) dobbing in third parties (c) compromising your ability to be useful. The manner of the amend must be appropriate, too, hence the option of a formal letter rather than a weepy hug-athon at Starbucks.