My short story with anxiety problems - could meditation be the cause?
Pleased to meet you Robert. 

It is very difficult to answer your question precisely however it is certainly likely/probable that practicing the meditation &amp; the accompanying mental solitude is digging/bringing up something (i.e., a disposition or mental tendency) buried deep inside your mind. 

I doubt you are doing anything wrong. As said, the mental solitude &amp; quietude of meditation will bring things up, including existential fear. This is generally related to the ego diminishing, which in the beginning will generally be somewhat traumatic. 

Even when the mind becomes increasingly calm, such as from Anapanasati, a certain threshold of calmness may threaten the (conditioned) ego, resulting in fear arising. 

Such fear may not be explicitly related to your personal childhood experiences because such existential fear is a normal event when "crossing-over". Some meditators use an old Christian mysticism phrase for this existential fear, namely, 'Dark Night of the Soul'. 

However, that your mind projects this existential fear into ideas of being abandoned by people may possibly relate to your childhood experiences &amp; underlying fear of aloneness. 

I offer the following suggestions: 


Quit meditating. 
Do the therapy, which is hopefully a kind of cognitive behavioral therapy (CBT) where you learn to rationally reflect/think that there is nothing to fear. This is similar to the Buddhist technique called 'wise reflection' ('yoniso manasikara'). 
If you decide to meditate again, meditate at a good competent Dharma centre with a group of people. I always recommend meditating with others is the best way to start meditation. The group vibe is helpful to reduce or remove anxiety. Also, hopefully meeting trustworthy reliable friends provides a necessary social support. 
Do not use recorded guided meditations when alone because these can take the mind deeper than the mind is prepared for. In general, avoid all guided meditations (including in Dharma centres) that go beyond the mere basics of letting go of thoughts &amp; observing the breathing. Any guided meditation that seeks to diminish the ego or observe emptiness, space or clear light should be avoided.