Contingency of god in classical theism

According to classical theism god is ontologically simple. This divine simplicity implies that  attributes which created things might interpret as distinct are in reality equivalent within god; that is god's intellect is god's goodness is god's will is god's essence etc. This gives rise to several difficulties but I'll just speak of one in this post. If god's will is in fact the same as god's essence, and god's will is free, then this would seem to imply that god is contingent. To see this just imagine another world, one that is exactly like ours only with one more electron in it. Since in that world god would've willed something different than in ours, and since god's will is equivalent to his essence, then the god who willed to create that world would have a different essence than the god who willed this world. Since his essence differs across worlds, different gods exist in different worlds, and thus his existence cannot be necessary. Aquinas attempts to answer this by making a distinction between absolute necessity and suppositional necessity; if his argument succeeds it would at most prove that there is no contradiction between god's will being free and god's essence being necessary, however it fails to answer the question as to how the gods of these different created worlds can all be one and the same.