A few light bulbs and warning bells are going off for me here.

First of all, what on earth is he doing holidaying with his ex-wife? This just doesn't seem normal to me. It actually makes me uncomfortable reading this. He hasn't cut ties with her and most definitely has not prioritized your own relationship. Deal breaker.

If the drinking bothers you, deal breaker.

Sorry, but in any relationship with a single parent, the significant other is NOT a friend or mentor. They are a family. If you cannot parent these children, deal breaker. If you cannot agree on parenting style, deal breaker.

I recommend sorting out some expectations regarding this relationship before moving ahead with it. Someone is going to get hurt and trampled over and I think that someone is you.

Sit down together. It is a good opportunity to get closer anyway. Lay your expectations on the table. What kind of priority are you in the familial relationship? What is your relationship with the children to be? Under what circumstances are you considered a parent? Are you to be in the position to dictate rules, behavioural expectations, and hold the youngsters accountable and discipline them?

Ultimately what is your role with them?

Is your boyfriend a 'Disneyland' dad or does he lead a realistic life with the children? What I am getting at is does he treat the kids differently when he has them than he would if he had them full-time? This is really a key point here.

What ought to be happening is that the children be treated no differently than if they were with dad full time - this means no slacking of the rules and expectations, no showering with gifts and events. Life with dad should be as normal as possible - AND it should reflect his own life he has rebuilt for himself. This includes you. If you are a big part in his life that shouldn't stop when the kids arrive at the door. This is entirely disrespectful to you. Nope.

I apologise for making you feel bad but I honestly think these things need to be said and considered before things get too far.