Advise needed - should I break this deal?

I need some advise on whether or not I should break a deal here.
The date is just before 1800AD, I am China. In the Ancient Age I broke a deal and my rep has not been too good, but I've played honorably since then and my rep, while still negative, is not TOO bad.

Near the middle of the 3rd Age I was able to do some fast trading which pulled me out of the tech quagmire in which I'd been languishing until then. It helped so much, in fact, that I was able to be pulling in a net gain of about 250gpt, have Research set on 60% and still get techs in 4 or 5 turns.

As we entered the Modern Age Greece has managed to catch up. I had 1 tech over them but was reluctant to sell it as it was my only advantage and I had plenty gold.

Then a huge world war erupts. I'm at war with 3 civs, one of which is Greece (they declared against me due to a MPP with England). I signed a few MA's to keep the dogs at bay and all was fine. I have a huge army and a great infrastructure.

BUT - just before war broke out I noticed Greece had acquired Fission before I'd got any modern age techs. I figured that'd be okay cos I would get Computers then sell to Greece for Fission and hopefully get UN and SETI. Alas, shortly thereafter war erupted and Greece wouldn't receive my envoy.

The war has been going on for some time. Greece has now built the UN (!!! in about 10 turns!). I have yet to get Computers (all my gpt deals fell through when war started. others have just expired and my research is slow enough not to give me another golden goode like that).

Now I have a Palace pre-build for SETI going on (well advanced too). I will get Computers in 3 turns.

Question: until SETI is built, Comnputers will be quite expensive. I have an MA with another civ against Greece. Should I break this MA deal now (it has about 10 turns left to go) and get as much value from Greece as I can by selling Computers (still theoretically Wonder-potential) for Fission (bear in mind UN has already been built) or should I honour my deal and wait it out?

If I do break the deal, should I also break my other MA's and make peace all over (England will give me 12 workers and all their gold (around a whopping 12gold) for peace), or is breaking more than 1 deal even worse for your rep?

Recap: Should I break a deal to reap as much benefit as possible from my only tech advantage?

If yes, should I break ALL MA deals at the same time (i.e. is it the same effect on my rep)?

I think your best bet is a war of all out global domination, one civ at a time (if that's even possible at this time.) You can't go around breaking deals in this game and expect to not be given your comeuppance.

If you can build 80 modern armors, 10 transports, 50 or so jet fighters and 300 mech infantries, you might could just roll over all your competition in 20 or so turns. If you harvest GLs like a pro, it'll be even easier.

That's just my observation, tho.

I recommend not breaking the deal. The only time I do this is if I have the UN and over half the power bar.

Do you think Greece will call a vote right away?

If not, then I think you need to build up a force and get some MA's and take the UN. Then you will have some time to catch up. The key is to get as many civs as possible to go against Greece.

Also China is militaristic - use a GL to build the wonder once you get computers.

Breaking the deal would be a risky move if your rep is that bad already. Greece can win with a simple UN vote and you have no power over it. I'd wait till the last minute and check with each civ to see if any of them have researched it or gotten it from Greece. If they have you can trade Computers for Fission without breaking your word again.
Getting a dogpile world war going against Greece is important to keep him from taking the UN win route. Even if your rep has taken a serious hit the AI's are more likely to vote for you (or abstain) if they are in a MA with you against Greece. If you can block his UN win, you should decide which win type is closest for you and rush for it before he can set up a winning UN vote. I can't help you with the type of win that is closest for you without a save game, but taking the UN away from the AI is a good idea no matter what your chosen route is.