Anyone with toddler & new baby 17m age gap, how did you manage?

I'm currently 31 weeks preg with a surprise Bub #4 I have a 6, 4 and 15 month old, the past couple of months has been extremely challenging with my youngest she has had days where 100% of my time and energy is on her she has become so much more clingy and more tantrums ! Not sure if it's just a phase but I can't imagine having another right now how will I cope? Anyone who was in the same situation how did you manage with Bub still young and new one please tell me it gets easier