Two under two

So I have two under two, an 19 month and and a 3 week baby I am having the issue of getting the toddler in his own room I would happily cosleep with them both (baby in next to me) however my toddler has discovered he loves the next to me and it’s just a hazard so I can get my toddler down at about 8/9pm but if he wakes up it’s game over which he 9 times out of 10 absolutely does i’m a single mum so I am yo yoing between them both I am so greatful my baby is the easiest kid ever bottle burp back to sleep or will chill out happily but i’m getting no sleep between them both mostly the toddler I have never ever done the cry it out method until now but I am kind of stuck here I leave him for 10/20 minutes go back in and he’s instantly happy and laughing and ready to play but when I tuck him in give him a kiss we have a cuddle for 5/10 and I leave the room it’s back to the crying I feel absolutely horrible I don’t want to do this but for his own sake I have to I feel he’s old enough now to know I love him and if he needs me I will come but he really does take the mick soon as i come in he’s happy as anything playing with toys like he hasn’t just cried I don’t leave him for longer then 20 and I am so close to him room wise it’s unreal is there any advice from one sleep deprived mum -He gets up at the same time every day regardless if he’s up till 5am he just likes a cuddle but it’s so hard right now to do that for him I feel like the shittest mum on the planet but any advice?