Tips for 2.5 yo

I’ve collet with my son basically his whole life. He was colic and had bad reflux so it was the only way to keep my sanity. Tried sleep training around 1 and failed bad, he would still wake up multiple times. I’m single and recently started seeing someone so I want to be prepared and have him sleeping on his own. ADVICE PLEASE 😭 2.5 is such a hard age