In a discourse on Mahābhārata today, I heard that, in the entire Mahābhārata, Vyāsa doesn't say one way or the other if Bhīṣma ever married or remained single. The speaker, Sāmavedam Ṣaṇmukha Śarma, in the video (Telugu) says Vyāsa has remained silent on the topic so it's possible that Bhīṣma married but chose not to have kids to keep up his promise made to Satyavati's adopted father.
From here, this is Bhīṣma's actual promise:
'Chief of fishermen, thou best of men, listen to what I say in the presence of these assembled kings. Ye kings, I have already relinquished my right to the throne, I shall now settle the matter of my children. O fisherman, from this day I adopt the vow of Brahmacharya (study and meditation in celibacy). If I die sonless, I shall yet attain to regions of perennial bliss in heaven!'
Above, Bhīṣma doesn't say if he's already married or not. He just says he won't have children hinting that he's currently married.
So according to Mahābhārata, did Bhīṣma ever marry or not?
If he didn't, are there any ślokas (or theirs translations) that conclusively say Bhīṣma did not marry?
PS. Please don't answer citing Harivaṃśa, Bhāgavata and other Purāṇas.