I think you thought this through well and planned it good. But sex could be an issue. 

Personally, I don't think it's right to sleep with someone or tell them that you love them when you know you're going to break up with them. I've done it to people and it felt wrong, unethical and direspectful towards both involved. 

If you want to respectfully keep up appearance don't get "benefits" out of it reaffirm love with a lie. That's got the potential of really leaving someone with trust issues and violates basic dignities. If you can't pull it off a breakup would be better than an outright charade.