These claims are false. Bulgaria joined the European Union in 2007; as a result, its GDP, exports, average annual wages, as well as a share of products created in their economies by the industrial sector increased. In 2006, before joining the European Union, Bulgaria’s GDP was estimated at USD 34.4 billion; in 2016, this figure increased to USD 52.4 billion. In 2006, the GDP per capita was equal to USD 6 107.71 and in 2016 it increased to USD 7 926.
European countries account for 78% of Bulgarian exports. Find out more about how Bulgaria benefits from EU funding.
In addition, the EU accession process helps the countries concerned build their capacity to adopt and implement EU law, as well as European and international standards.
For similar disinformation cases about Bulgarian membership of the EU see here and here.
Regarding the NATO claim, all the countries of Central and Eastern Europe which have joined NATO over the past decade have enjoyed peace, security and cooperation with their neighbours since then, Bulgaria included.