Wrong. Family planing is OK.
There's nothing wrong with it, since the child always has a CHANCE to be born, at least. Abortion = no chance. at all.
Let me walk you though an example. We have two couples. Couple A use the combined contraceptive pill and a barrier method (condoms). If that fails and they woman gets pregnant they have decided to have an abortion. Couple B use traditional Christian family planning methods. Both couples have already had as many children as they want to have.
Since couple A are using the pill the wife doesn't ovulate (much). When she does the sperm find it hard to get past the cervix anyway. The chances of her actually getting an egg fertilised is low.
Couple B are using the Rhythm Method. They're using the most draconian version which means they abstain from sex from the end of the woman's period until the end of her fertile cycle. Despite this the couple will still get several more eggs successfully fertilised than couple A. They are counting on the failure of implantation or early miscarriage (within the first month) to prevent the women from ever getting noticeably pregnant.
Couple B will kill more embryos during the remainder of their marriage than Couple A will. Couple A have taken every step they can to prevent fertilisation short of abstaining. Couple B have taken every step a good Catholic can take but their efforts are still not as good as couple A. Hell Couple A could probably have a couple of abortions and STILL not kill as many embryos as couple B.
Your argument is to say well Couple A choose to have the abortion. My counter-argument is that it doesn't matter. If abortion is premeditated murder as some pro-life people like to claim then the Rhythm Method and other NFP methods are murder by reckless disregard.
The simple fact is that no matter what you like to claim Couple A are doing nothing that Couple B aren't doing. The only difference is that they
know when they are doing it. (or at least know more often when they are doing it). Couple B know that their chosen method of contraception will kill several embryos. They ignore it. Couple A hope to never have to kill an embryo but when the woman does become pregnant they choose to terminate.
So it comes down to this. Lets assume that an embryo is alive, with all the rights you believe it should have. What number of babies are couple B allowed to kill by not caring that they die before what they are doing becomes more wrong than a single planned abortion?
Actually think about that question. I know you want to try to say it's different but is it really? Do a couple who will let several babies die by doing nothing really have less guilt than a couple who kill a single baby?