Hey OP, the post above just proved his actions, his contradictions and manipulations. He knows you very well; he used the keyword "marriage" to reel you in.
Control move#1: First he gives you a deadline on whether you get back together or not and tempts you with the offer of "marriage" as an incentive to give him another chance. What if you asked him to give you more time? Would he rescind his offer? Are there other contenders that he's considering? What's the rush?
Control move #2: Now that you told him that you wanted to be just friends, he wants to extend the offer so you could think on it some more- Why? Because you gave him an answer he didn't like nor expected. This is not love nor does love work that way.
Love is not about control, ultimatums or deadlines; it's about honoring, respecting and cherishing the person you are with and supporting that person and their choices/ decisions. He didn't respect your decision. It seems he's doing a lot of talking, where are his actions? He says he wants to marry you, why not ask you properly, heck do it in person? Why not woo you, date you, earn you? He wants you to move with him in 2-3 years; when you truly love a person, you can hardly stand to be away from that person for a minute! Why would he put you on standby to wait until HE'S settled? What about your needs? He has trust issues and so do you; that alone makes all of this a NO. I feel like he's pulling a bait and switch OP and I hope you protect your heart by following your brain and keeping the answer a NO.