Son won't sleep alone

My son is almost 3 years old. When he used to wake during the night we would lay in his bed and get him back to sleep. Now we know that was a very bad thing because when he wakes at night (could he 3 or 4 times) he won't go back unless someone is in his bed. It's exhausting. What's made it worse is that my partner ends up falling asleep in his bed and stays there for hours on end. I usually wait until hes asleep and sneak out. So now he only wants his daddy because he's like his bedtime buddy. If I go in to get him back to sleep he kicks off and throws a shouting tantrum. I'm also 4 months pregnant and really need my sleep! Not after judgement just suggestions to kick this bad habit and get him to sleep on his own. Thanks 😊