Car wont start unless I boost it checked battery and it reads 12.43 on multi meter and checked when I boosted it and went up to 14on meter

A healthy battery reading 12.43 should still be capable of cranking an engine fast enough with enough current left over for the fuel and sparks to start - that is assuming the spark plugs, etc. are also in good condition.

An off-load reading of 12.43 means little on it's own and is only one of a number of tests used to determine battery state. The most important test is to measure the battery voltage while the engine is cranking. It is reckoned a healthy battery attached to a healthy engine, starter, ignition system, etc. will ideally read no less than 12 volts - an analogue meter is best for this test.

12 volts is rather optimistic even for a serviceable system. 10 volts is more realistic and some engines will happily start at 9 volts as long as the cranking speed is still good but any lower and either the battery is in a too-low state of charge, is faulty or the starter motor is taking too much current and needs servicing.