Nope, not on. I spent the first couple of years of my relationship with my partner going to stay with his ex and kids in the country every weekend (without me of course). I would never put up with that again - it was awful. Even if you are 99.99999% sure that nothing would ever happen, it is just disrespectful to the current relationship. I always think in these situations... would I do that to the other person? If the answer is no, then that is your boundary.
@shraavar - I agree with this. He needs to be held accountable for his criminal behaviour. Drugging someone without consent by itself is a criminal offence. He will now go on to do this to another woman.
Baby no. 2 or 3 coming along forces you to accept being an imperfect parent too.
@myf - Actually, I get it. When my husband and I decided to end our 20-year marriage, we had the discussion in a restaurant too. It forces both of you to talk about it in a civil way, without things getting explosive. I guess there is no really great way to do it, or place to do it, but it made sense to me.