Everyone hates my custom civilization and want to fight me! But I'm peaceful!

It is quite easy actually. You need to have a military rating at about 100, otherwise you will be played by the other races. It is just how the game works. You dont have to use it, but otherwise you are considered as weak and will be attacked. Having a good diplomacy rating also helps to avoid trouble.

Other things being equal, the AIs see the weakest empires as resources to be harvested.  Having a decent military rating is indeed the most common way to avoid the problems you mentioned.  There are few more aspects worth mentioning, I believe.

First, the AIs generally do not begin serious threats and wars until the colonization phase is ending.  That is, AIs tend to expand first, and only start those other behaviors when their expansion has been halted.  Thus, one can often predict when that behavior shift will begin.

Second, AIs do not break alliances.  Thus, if you could get a full alliance with an AI, then that AI will not attack or threaten you.  However, such alliances are tough to get and take time you may not have.

Third, AIs already in multiple wars tend not to start new ones with the human player unless you are really, really weak, and sometimes not even then.

The beauty of that last one above is that you can sometimes bribe all the AIs into so many mutual wars that they leave you alone.  Just be sure to re-bribe them quickly if they sign a peace treaty.  Generally, it costs less to bribe the stronger one to start the war, but the weaker one may declare the war for technology that you have that the stronger one already has (and so you cannot bribe them with it).  Diplomacy ratings help here, as to the things that make your trades look better.

My rule of thumb is that every AI that has a higher military rating than I have should always be in two wars.

Jim is right and I might add that the AI's don't declare war randomly (there are exceptions though... Drath SA) but when they view "hostile" upon you. The minus and plus of their system of valueing is actually shown, too, and thus gives you multiple methods at hand to do something for this.

If you can't raise or compete in Military terms, then giving away one of your treaties is a major plus, as long as sending Freighters to them, and gifting them occasionally some worthless techs (*) or low-pop planets that will flip back soo.

And you'll get notice of some grave errors that you could do, as for instance, leaving Troop Transports in foreign terrain etc pp.

If your going to bribe them to war then occasionally a civ might seek help from you. In this case, gift something that you can spare, but make sure the color in which the text for the transaction is written in isn't red anymore (applies to *, too)The race will honour you with a "+ they appreciate our past help) and it is, in fact the sum of all + that show you you're doing everything right in the game, and if they fairly weigh-out some non-avoidable - (like 'militaristic' or 'our close borders') that will grant you an Alliance from y3 on.

Thanks, everybody. After taking everything into account I have managed to bribe the drengin off me. I only need to offer them something every 3 turns, I have built spin control centers and planetary defenses along with transports and defenders to circle my two planets. I have started an alliance with the Terrans and am working to get Torian to close.

THANKS FOR ALL THE HELP!!!