Why on earth did you let him live in your houses rent and bill free for 5 years? 
AND wait on him hand and foot?
Oh love, I know it’s early to be thinking about the future, and other men doesn’t even have to be part of your future... but I promise you that if you recognise what you deserve in a partner, you are going to be amazed in future at how much better it is!!
It is a relevant question about what you did in the house, and how that was funded.
There are no hard and fast rules in divorce. Yes, your cohabitation counts - but only if it was continuous. You say it was, but you also say it was you paying the rent and bills. Was that because he was living with you, but could show residency elsewhere? For example, was he on the electoral register at his parents and would claim that he was just “staying over with a girlfriend”, not cohabiting? That’s what I would claim if I wanted to fight dirty.
Even if you can include cohabitation, case law doesn’t firmly back up 6 years as a long marriage. It’s definitely in the maybe / maybe not camp. Your financial arrangements (him not paying rent) may have a bearing on that.
It would probably be in your financial interests to establish that he had taken financial responsibility for your children. I’m not suggesting that this is fair, only talking factually. I believe the phrase is “children of the marriage”. However, if he made no financial contribution when you were cohabiting, then I would guess (and I’m not a lawyer!) that that would be harder to claim.
So, if you are a “short marriage”, your claim is potentially limited to 50% of the increase in equity during your marriage. Even if you can get it from the house purchase, it’s not that long before your marriage anyway.
So you might be able to take another angle, as you would if not married - establishing a beneficial interest in the property. That would include if you had paid for significant renovation or remodelling, or provided valuable labour for those yourself. You’d also need to argue that it was intended for you to have an interest. As he paid all the bills except food, if I were him I’d argue that your contribution wasn’t ever intended by either of you to secure and interest in the property, but was simply your share of bills.
You are right not to agree anything without a solicitor. But it could matter, what you did to the house and what money you personally put into that.
What money have you put into the current house?
And what was happening when he was in your rented property before? Were you financially joined then?