How to insert a long text in a multirow on overleaf?

Question

Helle, I would like to create a table wit my 2 first row being multirows with one filled with a long text, followed by a 2 column's row. I don't have any issue to create the multirows or insert the long text in the typical columns but when I use the \multirow function my text overflows and messes up my table.

I used the following code :

{\footnotesize
 \begin{tabularx}{\textwidth}[h!]{| X | X |}
 \caption{Description of the selected algorithms\label{TABLEA}}\\

 \hline
 \multicolumn{2}{| c |}{Begin of Table}\\
 \hline
Algorithm & General Operation \\
 \hline
 \endfirsthead

 \hline
 \multicolumn{2}{| c |}{Continuation of Table \ref{TABLEA}}\\
 \hline
Algorithm & General Operation \\
 \hline
 \endhead

 \hline
 \endfoot

 \hline
 \multicolumn{2}{| c |}{End of Table}\\
 \hline\hline
 \endlastfoot

   \multicolumn{2}{| c |}{\textbf{Agglomerative methods}} \\
   \multicolumn{2}{| c|}{The notion of distance in this family makes it possible to identify cliques through relational proximities (in the network) that favor the exchange of resources..........} \\
   \hline
           \textbf{Hierarchical algorithm} with 4 different settings:  Euclidean distance / Complete linkage; Euclidean distance / Ward; Manhattan distance / Complete linkage; Manhattan distance / Ward.
           & The basic idea is to construct the hierarchical relationship among data in order to cluster. Each data point stands for an individual cluster in the beginning, and then, the most neighboring two clusters are merged into a new one until there is only one cluster left. The concept of "neighborhood" depends on the distance between nodes which is computed by squaring the Euclidean or Manhattan distances and grouping them into a symmetric matrix. The clustering method (here, complete linkage and Ward's algorithm) identifies the closest nodes to agglomerate them. We obtain a hierarchical dendogram which is cut to the desired number of clusters. \\


 \end{tabularx}
}

\end{document}

which gives me that table : enter image description here

Do you know how to overcome this issue?

I tried the same code as usual for \multicolumn but it doesn't seems to suit long text.