He sounds like an opportunist, and a dick OP. Hence texting at xmas (lonely time if year/free time, texting another woman when it was on offer, re-investing with you a bit now that you've bitten - when he was hardly begging to be with you before now, was he .
I think you do yourself a disservice by suggesting he has a hold over you- he doesn't- he was cracking on to another woman, you ended it and mostly stayed away. He's got nothing over you, you may have an emotional need that speaking to him feels like it fulfils but that's not the same at all.
Focus on yourself, don't beat yourself up. Not clicking with anyone or fancying dating only means you aren't ready or wanting to date right now, it doesn't mean its because you really like him or that he's some sort of opportunity.- he just sounds a bit pathetic tbh, and you clearly need and deserve more.
I'd stop worrying about what he thinks, he didn't care about what you might think when he was looking elsewhere? Delete him on Facebook, justify nothing to him, try to stop worrying what it will all seem like to him. Others are spot on to say that each time you do, or each time you reply you boost his ego and in return affect your self esteem.
Delete and block OP, delete his number, start doing yourself favours!