How will our assets be split

The starting point is always 50:50 then you look at reasons for departure from this. And start to negotiate.

Is your ex likely to agree to your proposal?

Clearly there are enough assets to meet everyone's needs but all assets need to be included.

You will also need to include the income from the buy to let properties as your income if you are paying the tax on it. You can't ring fence it on the grounds that you want to give the assets away to your children.