Create integration with Sendy

Im looking for a simple integration with Sendy API ( API info can be found here https://sendy.co/api ). What I need is to have a custom multi-select picklist field on contact object and Lead Object( I can create this) that will contain multiple options that represents different email list we have with Sendy. And what i need is something that when a value from the picklist is added it will add the contact or lead to that mailing list and when picklist value is removed it will remove them from the list. Also to note that if many are added or removed from the pick list value at the same time I will need the same to happen, remove from the selected lists or add to the selected lists. Also will need an interface to make the mappings for the picklist fields to Mailing lists in Sendy as these will be added and updated over time. Second peice is, if possible query the Sendy list(s) and if a subscriber unsubscribes from the list to remove the picklist value(s) from the contact or Lead. This can be set to run on a schedule, which if possible i would like to have an interface to adjust the schedule and also have an option to run on demand.