I think it's unclear whether this is an actual inheritance following a death, or an early release of future inheritance following a downsizing (i.e. a gift). Given the reference to an inheritance from my 'parents' (plural) it seems distinctly possible this is actually a gift but we don't know. OP if one or both of your parents have recently died, my sympathies.
Now if her DH knew this money was coming, it's absolutely sensible of him to wait for it to arrive before divorce. It may be because he felt less trapped, but it's also actually fair - this money should be considered when deciding how to deal with finances during the divorce, because it's money OP has. OP I know it's hard but the reality is that you actually are in a better position because you have this money than if you didn't.
The way finances work in divorce, is that (assuming a long marriage) if both OP and her husband are in a completely equal financial position, marital assets would be split 50:50. Whether or not this 'inheritance' is considered a marital asset would depend on lots of factors we don't know, but starting point if an actual inheritance would be it isn't, and if a gift it isn't if clearly given to the OP. OP should rely on her solicitors' advice for whether or not they consider it to be a marital asset. From the sounds of the OP, they've said likely not (she doesn't mention having to share it, just having to use it for her housing costs).
Let's assume this money isn't a marital asset. The court would look to see whether OP (or her DH) should get more than 50% of marital assets. They look at things like making sure the children have a home, parties financial position, current and future financial needs, everyone having a roof over their heads, future earning capacity, age, standard of living they've been accustomed to etc. Given OP is a lower earner, if she didn't have this inheritance, she would get more than 50% of the assets if she'd struggle to house herself from her income alone.
With the inheritance, it may no longer be a concern that OP won't be able to afford to house herself. That's probably what her solicitors meant when they said that she'd need to use this inheritance for housing. Whilst hard for OP, that's fair - why should she get more than 50% of the martial assets just because the DH earns more IF OP has a large cash amount that she can use herself.
The inheritance itself is unlikely to be split (unless it's a marital asset for some reason - see above), but it's a similar impact.
Now if marital assets are limited, and this inheritance is massive, it's always possible that it could mean the DH gets more than 50% (as he needs to be able to house himself too! and he's only been a high earner for a short period) but that seems unlikely in the circumstances (he's on 100k so presumably can easily afford rent and the OP doesn't mention significant debts).