The idea that the Buddha snuck out in the middle of the night and simply left his wife and child behind is a later legend not found in the suttas. This is what the suttas have to say:
… akāmakānaṃ mātāpitūnaṃ assumukhānaṃ rudantānaṃ, kesamassuṃ ohāretvā …
… although my parents wished otherwise and were crying, I cut off my hair and beard … (MN 36)
It is clear from this that he consulted his parents. Although they were not happy with his decision, it seems reasonable to me to assume that the Buddha-to-be would have ensured his wife and son would be properly looked after. The old idea that the Buddha was irresponsible does not come up if we rely on the earliest sources.